Player on floor and another player jumps on them and you don't see that excessive? Sorry, that just doesn't compute, particularly when the NFHS has explicitly said they want that to be a foul. Why would a player get to jump on top of someone at anytime in the game of basketball? To allow that simply isn't basketball.

Quick List of basketball plays/actions:

Pass and Crash where we've got nothing and the play goes the other way. But one player ends up on top of another on the floor.

Two players get tangled up rebounding/running the floor. One stumbles the other trips over them and one lands on a another. No where near the play the both get up and move on.

One player falls/down get knocked down and now on rebounding action trying to avoid stepping player/players stumble and fall landing on each other.

PLayer dives into a the bench of their/opposing team end up on top of someone.

This is just a short list of reasonable things that happen in basketball game where one player ends up ontop of another pretty regularly.

I'm not saying kids can swan dive into opponents with the ball on the floor but the blanket statement of jumping and landing on player while in the midst of making a play has to be uniformly applied as a foul seems nonsensical.

Players are allowed to reach for the ball and get to the ball athletically (jumping/diving/etc). If that play creates contact we've now got some factors to look at: A) is the contact creating any immediate and clear adv/dis that wouldn't have been gained without the contact B) is passing on this type of contact as incedental going to promote/allow/lead to rough play.

There are more aggressive and physically damaging or taxing things that can happen to a player that are perfectly legal than having a player on top of them. So why would this ALWAYS = rough play? If two players are tied up in a loose ball standing and one goes to ground pulling the other player down on top of them would you have a foul then?

I can see and do see situations when the contact is excessive or dangerous and/ creates an unfair adv/dis so in those situations I would call a foul. To say I'm going to automatically call a foul because in the course of a play one player ends up on top of another . . . I don't think so.

Maybe in your mind "jumping on" and in my mind "jumping on" are not covering the same range of possible actions, but to say its absolutely always going to be a foul is not something I'm comfortable saying.

A key, in my mind, is "jumping on" as opposed to "landing on". A1 is on the floor. B1 "jumps on" him for whatever reason. Not gonna say "absolutely always" to this (or most things) but there's a good chance this is a foul.

Most, perhaps all, of your examples are apples and oranges relative to the play being discussed.

If a player is on the floor and another dives/jumps/etc. onto that player, even in an attempt to get the ball, it is a foul, every time. At no time is deliberately jumping onto another player a legal play. That is quite different than stumbling or tripping and ending up on another player....which may or may not be a foul depending on how it all happened.

Again, from the NFHS POEs:

If one player is on the floor with the ball and the other dives on, those are not equally favorable positions.

NFHS POE states that they don't want jumping onto others to try to create a held ball or go for the ball, but it does specifically state that contact is incidental contact if both players are in equally favorable positions.

Maybe I'm reading this with my own view point but if contact when both players are in possession of the ball or the ball or players wouldn't/don't move anywhere else that seems like pretty equal or favorable position in terms of impacting the play.

In unrelated news FIBA has no such POE.

I also see a dramatic difference between a player jumping/diving from 5 feet away to crash into a player on the floor and a player standing over another player who has to leave their feet to get the ball as the player on the floor tries to rip the ball away from hands.

In both cases the player is "jumping" down onto the ball/player but contact, rough play, access to the ball are not equal. I think this may come down to either:
A) how we're reading to interpreting the POE (that again doesn't exist in 90% of games I officiate)
B) What we are considering "jumping" onto a player on the floor.

I would agree .

Except that its not the jumping we are calling the foul. Its the landing that causes the contact. If there is jumping but no contact at the end then there can't be a foul. So really what needs to be cleared up is the difference between leaving your feet and ending up on a player and "jumping onto" a player. IN both cases we are landing with equal or at least similar forces in contact and accoriding the POE that gets referenced the key difference would appear to be the amount force generated on the take of "jumping".That seems like a vague and grey area to be absolutely a foul.

In my games players don't accidentally fall onto other players who are already prone on the floor. So it is pretty clear-cut to me that a player on the ground with the ball is fouled when another player jumps on him in order to get the ball.

Making A Play ...
 

This (above) is the key, "while in the midst of making a play". We're not talking about random plays here, i.e., accidentally tripping and creating a domino effect. To me, "making a play" means a deliberate effort to get the ball. When players attempt to "make a play", the principle of advantage, and disadvantage, always has to be considered in any interpretation, and most interpretations of one player deliberately diving on another player in an attempt to get the ball would involve a foul being charged.

Agree with all below:

Would you allow such action if two players were vertical instead of horizontal with one standing and holding the ball?

Good question. Would I allow I player to dive or leap or jump to make a play at the ball absolutely.

If they never touched the other player obviously no foul.

If the jump has them tie up the ball and then land belly to belly or side to side with the offensive player simultaneously. Since the ballhandler has no expectation of time and space, and the contact is not significantly impacting the play and I don't feel like its leading to rough play probably calling a tie up.

If the jump has them get to the ball but go and displace the player or roughly move the other player. Probably foul but again intensity, level of contact we've allowing, etc. Come into play.

If they don't get the ball or need to go through to get the ball. And there is substantial contact. Foul

Again all I'm asking for is the same leeway in determining the result of the play. Will a lot of these result in fouls probably, but that doesn't mean they automatically should.

PLayer can belly up and bump players with and without the ball all over the floor. I get that a prone player should be protected in a similar way to a shooter because of their defenselessness. But every bump or collision with a shooter is not always a foul. IN the OP the prone player is in possession of the ball it is no longer loose so the defense is entitled to defend them, and they are not entitled to time and space. If they are roughly landing on players or not playing the ball or knocking them off their spot. Call it away. If they just end up tieing up the ball and part of all of their body ends up on top of the opponent as a result. The fact that they "jumped" to make a play on the ball seems like a silly reason to automatically call the foul.

Bump ???
 

They can? As a blanket statement?

They can. Sometimes it will be a foul and sometimes it won't.

Not on purpose.

I understand your thinking here but I don't think its reasonable to assume that blocking cuts, boxing out, bellying up to ballhandlers, running through the lane, posting up and post defense, denying players etc when contact we deem as incidental is occuring "accidently". People are taking lines and angles for a reason and they are being coached to create or intiate the contact on both offense and defense constantly.

Indeed, but these are not at all the same as diving on a player who is laying on the floor.