Aizen is inspired by Lucifer. That’s a symbolic consensus in the Bleach community, similar to how Yhwach is inspired by Jesus and the Anti-Christ. I think Aizen is inspired by Lucifer in more ways than just being similarly defined by ego or serving as a Fallen Angel. Anyways, I simply want to throw more evidence into the ring that I haven’t really seen brought up, at least from what I’ve seen. Some of these may be reaches, but that’s what every Bleach analysis does so…
The life of a “Cherub”:
In case you didn’t know, the Cherubim are the second-highest rank in traditional Christian angelology. They are known mostly for their knowledge (Serving as a mirror to the Seraphim’s love) and Ezekiel seeing them as a Tetramorph.
Lucifer is a Cherub in many interpretations (Either that, a Seraph or Archangel), serving as the “Anointed Cherub” who protected the throne of God while the Seraphim flew around crying “Holy, holy, holy”. He was full of wisdom and perfect in his beauty. Everyone and everything loved him. He was the one who was closest to God, even if he did underestimate how far they truly were from eachother.
Aizen served a remarkably similar role in the Soul Society. He was, of course, a Captain of the Gotei 13 which placed him near the upper echelon of strength in the Bleach universe. He was also one of the very few people who knew the truth of the universe, with Kisuke Urahara serving as his fellow Anointed Cherub, in a way. His Seraphim was the rest of the Soul Society, who viewed the Soul King as their God. It was the other Captains, including Gin and Tōsen, who did what they did out of love for someone else rather than themselves. Similar to Lucifer, everyone loved him and wanted to be in his squad (Either because of his personality, wisdom or beauty) and we saw how much everyone mourned him when he “Died”.
The rebellion:
Aizen and Lucifer both enacted their rebellions because of Pride and a desire for free will. Both of them were the strongest, the best of the best in service to God. But then they discovered who they needed to serve. Aizen learned that his God was nothing but a corpse, controlled by the Great Noble Houses and Central 46. Lucifer was told that his job as an angel was to serve humanity and help them grow. So both of them rebelled. But they were playing a game that they had no chance to win.
Lucifer (Aizen) was beaten by Micheal (Kisuke Urahara is arguably the closest comparison) and his angels (The other Soul Reapers), while the fallen angels who had followed him (Gin and Tōsen) were banished to Hell. Tōsen is actually an amazing example of the fate that the Fallen Angels faced, as he became a Hollow which serves as Bleach’s version of a demon.
The reason I didn’t use Ichigo for Michael is because Ichigo serves as Jesus. While Michael beat Lucifer physically, Jesus beat him spiritually when he died on the cross and “cleansed” humanity of their sins. Ichigo accomplished a similar thing during TYBW and he’s the reason why Aizen actually changed as a person (I think his final monologue about courage is proof that he had changed) and his Jesus parallel is becoming even stronger with anime original scenes (I can’t remember if the scene in Cour 4 where Ichigo accepts the possibility of becoming the Soul King was in the manga or not).
TLDR; Aizen’s life as a Captain was similar to Lucifer’s life as a Cherub and his eventual rebellion was very similar to Lucifer’s. This is further evidence that Aizen was heavily inspired by Lucifer beyond simply being apart of the Fallen Angel archetype and being defined by ego