The first swimming

I wonder which came first: humans learning they can swim, or humans learning they can't swim?

By which I mean: did some random prehistoric human boldly go charging into the water (to what end? to catch a fish? to escape from something? to get to the other side?), never suspecting anything could go wrong, and end up dying?  Or did some random prehistoric human end up in the water (how? by accident? murder attempt?) fully expecting that this would be the death of them, and survive?

I'm told that you put a human baby in the water they'll swim intuitively, but older kids still need swimming lessons.

Some land animals seem to swim intuitively.  Did humans originally have that intuition?  Or did they figure it out from copying the water?

Is the fact that we can't breathe underwater instinctive, or hard-earned knowledge passed down through generations since time immemorial?

If it isn't instinctive, did it take several drownings to figure out that the reason people keep dying in the water is because they try to breathe underwater, and they should hold their breath to survive?

(Did humans ever hold their breath for any other reason before they started swimming?)

At some point, humanity (or, at least, the precursors the predominant culture in which I grew up) must have internalized and normalized the idea that humans can't swim naturally, because swimming lessons became a thing. 

Also, someone at some point came up with the idea of standardizing and naming different swimming strokes, some of which are weird. (Butterfly? WTF?)

And some other swimming strokes may well have existed but are lost to history. (And still others probably exist within other cultures and haven't reached me.)

You could also follow this same line of thought for diving.  Why did someone first think they even could do it?  Or did people never think they couldn't do it, until several people broke their necks.

Do other land animals dive?

Is figuring out how high you can safely dive from (and how deep the water needs to be) instinctive or learned? (I dove off a three metre board once - into an Olympic-sized pool, properly supervised - and it felt unsafe. It felt like a fluke that I didn't die, not like a safely reproducible thrill.)

And, again, enough people dove enough times that it became a normal thing to be able to do, a normal thing to learn in swimming lessons, normal enough that nobody even thought I was weird or reckless for wanting to try the three metre board.

I wonder if there are other, similar things related to swimming that were once (or are elsewhere) considered culturally standard, but are now lost to history (or haven't reached me).

I'm sure that sometime, somewhere, within the full scope of human history, there have been people who never once thought swimming was a possibility.

And I'm sure that some other time, somewhere else, within the full scope of human history, there have been people who never once thought that swimming was difficult.

But I do wonder which came first.