[angryoldfatman]

Since it’s a tree and not a ladder, what happened to all of those other branches?

I mean, the dead limbs are all over the ground. Maybe not lying next to the tree they supposedly fell from, but there they are.

[JimSEA]

We are the surviving species but, as recently as 18,000 ya there were others.

[BroJoeK]

angryoldfatman: "Since it's a tree and not a ladder, what happened to all of those other branches?"

Dead wood, so to speak.
Some species survived for hundreds of thousands of years before conditions or competition (i.e., us) drove them to extinction.

This chart shows over two dozen pre-human or early-human species or sub-species before our own homo sapiens sapiens.

Here's another visualization of the data:

[central_va]

I am waiting fro an ape in captivity to birth a fully formed nuclear scientist.