The other elements of the story just bend to the main character's plans, there has been no real challenge for the main character no real challenge or no real conflict when everything is 'planned out' by the main character and goes exactly how the main character plans.
Examples;
1. The ancient one, even if she couldn't see the main character's future, would still be wary of the main character for being a god's puppet, and she would at the very least demand that he does not harm the Earth, and even then it's a major stretch that she would teach him magic, she would most likely see him as a threat to the earth and eliminate him then and there, just for being connected to a 'patron god'.
2. The whole entire scenario with the black widow is just one whole pile of plot convenience BS, first off SHIELD didn't recruit black widow at all in fact they were hunting her and trying to kill her, and while yes it's entirely possible for SHIELD to try and brainwash her or use her trauma to manipulate her, it's harder because she can know the signs of brainwashing from the red room, and even then the delivery for such a plot development could have gone over a lot better if implemented at a slower pace, not just 'Oh, by the way, I noticed you're still brainwashed, yeah let me just get rid of that brainwashing and then add my own brainwashing to make you 'fall' for me.
Now let's mention the main character design, honestly everything the main character does is defined as the typical manipulative, power-hungry fool, that everything just falls into his lap. Honestly, it's probably better if this was a cultivation novel at this point, it's that bad. At least with a cultivation novel, you can use the excuse of 'oh the heavens are smiling upon me' or 'I've been blessed by the heavens'.