What happened, the uncontested facts:
Trump said "I would like you to do us a favour, though" right after Zelensky brought up the aid.
While this happened, the aid was paused, on orders from the White House, with no explanation given at the time.
After the whistleblower report came out, they released the aid and claimed it had been over corruption concerns.
Okay, so now the questions:
Why did Trump say "do a favour, though" right after Zelensky talked about aid? Why is it that it just happens the aid was withheld for no reason? If the aid getting withheld was about corruption, then why did Trump not once mention the word corruption in the call, and in fact actively hindered anti-corruption measures, and only brought up the "corruption" that is of personal benefit to him if investigated: Biden, and the "Crowdstrike" conspiracy theory.
Trump has given no reasonable explanation for all this, and the aid was released only after they knew about the whistleblower (in other words, they got caught). And none of this was official, declared foreign policy with USA's interests in mind. Trump was doing all of this through Giuliani and other unofficial channels.
Not only has Trump not given any believeable explanation, he has actively tried to prevent everyone from testifying. He has multiple times been given the chance to come testify or send someone testify to give his side of the story under oath. Yet he has not done so. Does all this sound like how an innocent person just investigating corruption would react?