Not sure what you find rude there.
As for the Ajax GK being top 50 by default, isn't that a stretch? This isn't the 70s.
Your list has Emiliano Martinez in the top 10 and he plays in the PL, for their 11th side. So if we follow your logic, there should be around 10 GKs in that league alone at a similar standard. 3-5 top leagues with similar standards, plus South America + mid-tier leagues (Portugal, Belgium, Russia, Turkey, Switzerland etc) having at least 1-2 good GKs, you're pretty much entering a loop here where "barely top 50" is a possibility you cannot dismiss, especially given how Onana barely featured in the CL that much apart from one good run. The rest of his showing wasn't really impressive and he's struggled a lot actually.
There are times where Ajax did not qualify for a group stage and he was partly to blame. Properly, not the FIF Handa treatment. Sure, he was younger, but he only became a bigger name due to De Ligt and De Jong coming up.
I specified that I rate his reflexes highly, but that's something a lot of young good keepers have. He has bad positioning, is rather eccentric in going out of his box, makes silly mistakes as he tried to play with the ball a lot, but sometimes gets fancy and I don't like his aerial ability, nor his ability to dictate a defense in set pieces.
I've been watching him for 5 seasons now, sometimes from close up since he's played a lot over here. I was hoping he'd be a name for Inter and that's why I kept a closer look. But he's underwhelming when it comes to what Inter should have as a GK.
From anyone u25 out there I rate Donnarumma, Simon, Meret, Dragowski, Livakovic, Rajkovic, Kepa and Audero at the same level or higher. I reserve judgment for that Brighton guy who I sort of liked and I've no clue if there's any Brazilian starlets, given how Alisson and Ederson have popped up as top choices recently. Plus, I'm probably missing some Germans who always have top GKs.
And yeah, I wouldn't trade many of those over Handanovic this season. Maybe next season. Donnarumma and Simon are the two guys I'd want but they're impossible. So, hard pass on anyone else there, unless it's for a 2 year fix. Including Onana.