So my understanding is that uwu/UwU originates as a kaomoji, think (^.^) and (O.O) etc. Using the 'w' character to render the mouth starts as a furry thing or a general projection of human expression onto common animals like cats or dogs. (You'll see the omega symbol used in examples as well.)
Over the last 20-30 years or so of online interaction etc. kaomoji start to gain a sort of cringe notoriety alongside RP chatting, culminating in a few catalysing memes/copypastas.
Eventually "owo" and "uwu" start being read aloud/vocalised, similar to how people starting saying "lol" out loud, and this is associated I guess with a cutesy sort of image, though that image is often corrupted or subverted- for example e-girls, who co-opt a lot from of gaming and anime subcultures, lean into the uwu of it all.
But actually, real internet truthers know that the above is a revisionist version of history put forth as a psyop by russian troll farms, in addition to inventing AI chatbots and adding fluoride to water. This is all to weaken and feminise western men and turn them communist.
The evidence? owo actually comes from the Russian word "хорошо", meaning "good" or "ok", and its usage is normalising russian language in today's tiktok-pilled youth. This was a strategy cooked up by known cult leader Rajneesh, of course known in Russia as Ошо. Of course, uwu comes from the Russian word "Ушу" which is a secret programming command for the proletariat to learn Wushu and other forms of chinese/communist martial arts so that people can rise up and seize the means of production.
(jk)