Essentially Adam’s sin was idolatry of self. He poo pooed what God had instructed him to do and thought that he knew better than God. Satan essentially said, “just be yourself”. Heard that before? You become what you worship, and worshipping self leads to you being more like yourself. Jesus tells us to deny self for good reason. We are to be found In Christ. On judgement day you don’t want Jesus looking at you and seeing your own self. You want Him seeing Himself in you. This won’t make sense to some but those who have ears to hear will get it.
This was the sin of Adam. Self idolatry. Jesus fixed that at the cross and resurrection. Be found in him.
This also fits with the image of the beast not being a physical idol like most believe. The earth dwellers are as a whole the idol/image of the beast. The image of the Beast is the antithesis of the bride/body of Christ where He is the head. Do you get it? These earth dwellers worship self, just as the dragon wanted Adam to do in the garden.
Let me also add that those who vehemently deny Jesus and His finished work on the cross, do this because of pride of self. They worship self. Pride goes before the fall.