I disagree with your assumptions, and appeal to authority.
There are more details readily available that are known, but some we may never know. Booth barricaded the door upstairs. So the security guards would had hard time getting in upstairs. As soon as Booth landed on the stage he was chased by Major Joseph B. Stewart and footlights. They had to climb onto the stage over the orchestra pit.
The drop from the balcony to the stage is not certain, some records put it at 12', some at 15'. Basically a first floor (2nd in US) window. There are ample stories where people fall from heights with minimal to no injury. The stage is wood scaffolding, that gives on impact. It is elevated, and there is low-headroom space under it. "At first, the crowd interpreted the unfolding drama as part of the production, but a scream from the first lady told them otherwise."[0] There were screams and pandemonium. [1] Smithsonian has even more details, including how someone recalls Booth's spur getting caught while jumping in the flag draped over the front, potentially slowing his fall, but landing on hands and knees.
[0]: https://www.history.com/.amp/topics/american-civil-war/abrah... [1]: https://en.wikipedia.org/wiki/Assassination_of_Abraham_Linco... [2]: https://www.smithsonianmag.com/history/abraham-lincoln-team-... [3]: https://www.ushistory.org/us/34f.asp
And as Booth is being a Marvel action hero (a man in his 40s), everyone is standing around twiddling their thumbs? Including the military detachment outside. The story is not realistic on any level.
Walking -- running, even -- on a broken ankle is totally normal, for like fifteen minutes or an hour. It's after the swelling sets in that you get all hobbling mclimpy.
Having broken my own ankle I could totally believe that after the initial "ow, fuck, that hurt", Booth could totally have not realized he'd busted his ankle until he tried to get off his horse and his ankle went NOPE.
Anyone could just walk onto the White House grounds without challenge for a really long time, for example.
Also I did not know there were conspiracy theories about the LINCOLN assassination. It's very quaint!
What I'm suggesting is that the official account makes no sense. Mary Lincoln Todd waits for Booth to do all of his theatrics, instead of immediately screaming "EVERYONE WITH A GUN SHOOT THAT MAN".
I am not suggesting it anything beyond that. But I am not terminally naïve.
I challenge you to look for good historical analysis of the situation. There isn't that much.
I think you're using videogame logic to analyze a human situation. People do not react that way.
I would say it is equally likely that Booth did some parkour move to drop 15 feet and be minimally breaking his leg? Or, more likely, the adrenaline, and flight mode, after killing someone allowed him to not even feel the pain in the moment?
They were at a theatre enjoying a show with the President of the US present, why would anyone have a gun on them?
You're putting a lot of weight on "you can't hold onto something from a 15' drop" to dismiss everything, even though there were hundreds of witnesses, many of whom were interviewed about the events.
Why don't you go ahead and tell us your theory of what happened. I almost guarantee it is more outlandish than "he held onto a knife from a 15' drop"
And he timed the shot to be at a point where everyone laughed during the play,meaning many people just had no idea what was going on.
So, what's your theory of what happened?