People largely vote for who they resonate with on a gut level, not based on policy. That's why the taller candidate almost always wins. Objectively, Elizabeth Warren had the most extensive well thought out policies amongst the Dems, but that didn't actually help her much. Trump had next to no actual policies or plans for how to enact the few that he had. People didn't vote for him for his policies. The Republican party didn't even put together a platform last election because they knew how irrelvent policy actually was in comparison with the cult of the Trump personality.

I'm not much of a Biden fan (because of the disregard for the body autonomy of so many women) but I know a lot of people who genuinely think he's great. They feel like professionalism, competence, and honor have been returned to the White House and they are happy with the things that he's already doing, such as killing the Keystone Pipeline permit, rejoining the Paris accords, mandating mask wearing on all Federal properties, bolstering federal non-discrimination rules for LGBTQ+, reaffirming DACA and stopping construction on the stupid wall. Those are all things that Democrats value and they happened in just Biden's first few days in office. They see him as someone who can take our country back from being the world laughing stock it has become and return it to humanity, science, and sanity. I'm not surprised at how many people genuinely like and approve of Biden as a leader based on those things. He has a long history of bi-partisan work, and public service and is moving quickly on substantive issues that they care about. I'd say that so far, amongst his party, he is widely liked and approved of.