[Mudtiger]

“However, while a metaphorical tree seems helpful in visualizing evolution, nobody pretends all of its trunks, branches & points of connection have yet been found.”

I appreciate the discussion on this topic. I think it an understatement to say that all points of connection have not been found. From the tree you posted, I don’t see any points of connection (common ancestors) — only cousins or siblings. There is assumed to be a species at the node points where the branches split, correct? But none are identified. Maybe this tree is too dated?

[BroJoeK]

Mudtiger: "There is assumed to be a species at the node points where the branches split, correct?
But none are identified.
Maybe this tree is too dated?"

Consider the case of Neanderthals, where ancient DNA was recovered & analyzed.
It showed that Neanderthals were not our direct ancestors, that our common ancestor preceded Neanderthals by several hundred thousand years, but also that there had been some interbreeding between Neanderthals & modern humans around 50,000 years ago.

That's a lot to learn which we didn't know before, and iirc, similar analyses have been done on pre-human Denisovans and maybe even "Hobbits" from Indonesia.
My point is: with DNA analysis we can say for sure who was related to whom & how.
Without DNA all we can do is make educated guesses.

And there's been no DNA recovered from 99.99% of the fossils ever found, so exact relationships are unknown.
Further, the evidence suggests complete speciation between two related populations can take circa a million years.
By that I'm suggesting:

1. Separate breeds or races (i.e., human races) can develop in nature in a few tens of thousands of years.
   Breeds & races readily interbreed.
   
2. Separate sub-species (i.e., humans vs. Neanderthals) may take hundreds of thousands of years to evolve.
   These subspecies can still, on occasion, biologically interbreed.
   
3. For normally non-interbreeding species of the same genus to evolve can take a million years.

Again, point is: there's no way to tell, just by looking at fossils how much interbreeding went on, or, indeed, just how closely related two species may have been.

So that's where the gaps in the fossil record get filled in by evolution theory, which says: ultimately, every species can be traced back to its common ancestors, even if those were many tens of millions of years ago.

To pick an example, modern DNA confirms theory of ancient common ancestry among elephants, hyraxes and manatees.
However, it's doubtful if fossils for the actual ancestors have been found, and there's no way to say for certain if any particular fossil is, or is not, directly in those lines.