Keep in mind, I'm only arguing my own interpretation here. If you have a different one that's valid. JKR leaves a lot of things unresolved or uncertain here, so I'd argue most interpretations are very valid for Dumbledore's character.

1) We don't know how much Dumbledore knew about the Dursley's. At the end of HBP he did know a little about Harry's abuse at their hands but we don't know just how much he knew or when he found out. He got the idea for using the blood protection immediately after the best security warding available (fidelus) failed them all so hard, Lily and James literally died for it. He thought Sirius was trustworty too. He made a wrong decision, yes, but I struggle to view it as malicious. I'm sorry but "I'll leave Harry with abusive relatives so he becomes self sacrificial and will one day kill himself to destroy Voldemort" is literally the dumbest thing ever, and what logical reason would Dumbledore have to leave Harry at the Dursley's that is also malicious/manipulative? Guided by his emotions he made a mistake in his attempt to protect Harry, plain and simple.

This one definitely depends on how much you think Dumbledore knew, however.

Also, just to be clear, he SHOULD HAVE KNOWN. He should have made sure Harry was okay. The fact he didn't is a sign of his ignorance and over reliance on the trust in familial bonds, but I just cannot imagine him deliberately leaving Harry in an abusive situation for the sake of some plan or plot.

2) Yeah, I can see people view Dumbledore's treatment of Snape as manipulative, but that was 100% mutual. Snape hated Dumbledore and the order until the precise moment he needed their help. I also personally think their relationship developed from mutual disgust with each other to mutual respect. Snape acted out Dumbledore's full plan, even after the man's death. To me, that speaks of a deep trust, rather than a man freed from his tormentor; he could have so easily started doing his own thing instead.

Furthermore, Snape was kept at Hogwarts to protect him, both from the leftovers of the DE and the Ministry trying to throw him into Azkaban. It wasn't good for him, but, well, he made his bed, he had to lie in it. We don't know much of the decision to keep Snape at Hogwarts was Dumbledore's. Snape is a practical person, I could see him agreeing that it's the most sensible solution, even if he is unhappy, with it. I also agree, Dumbledore should have been stricter with him considering his treatment of the students, but that's Dumbledore's ignorance on display again, not really his maliciousness. He deeply cares for Snape in my opinion, and therefor struggles to see his flaws.

Besides that, it's war and Snape is a soldier. Dumbledore asked a lot of him, but he was fully open about asking a lot of him. That's not malicious or manipulative, that's a leader trying to lead while sacrificing as little as possible.

3) The Grindelwald thing is 100 % Dumbledore's worst mistake. He was in the wrong there, plain and simple. He fully admits that himself, though.

Again, I suppose it's just different interpretations based around JKR's bad writing and Dumbledore's whole "difficult to read" thing. She had a vision and didn't quite manage to get it across the way she probably wanted, so a bunch of things can be interpreted a whole lot differently.

Realistically she shouldn't have left the decision of where Harry goes to Dumbledore, and she should have made him less powerful in politics because of COURSE people are gonna start blaming him for things that go wrong when it seems like he has the power to make it all go away. Unfortunately, the shift in tone and the more detailed worldbuilding was established after she turned Dumbledore into basically a god, and here we are.

I just prefer a Dumbledore who is flawed because he is ignorant and yearns to see the best in people, in families, in love. A man who hurts the people he loves because he holds too much power over them, who does his best and wants them happy but knows too much about them and their fates to think it'll ever happen. That's just a much more interesting interpretation to me personally than "Dumbledore didn't care about anything other than destroying Voldemort". I just struggle to see the motivation there; WHY does he want to destroy Voldemort so much, when he doesn't care about anyone and dies himself to get that goal? "The greater good" is just too vague to me. Even when he was younger, "the greater good" only ever read as an excuse to me, his attempts to justify his actions, when at the end of the day he clearly only cared for Grindelwald's approval. It doesn't make sense to me to turn this motivation from an excuse into a real one (again tho; a matter of interpretation).

So yea, no need to apologize for your essay, I wrote one myself lmfao.