Biden is a weak and uncharismatic candidate who don't have any noticeable policy suggestion but just merely promise to undo what trump has done like going back to to he climate pacts and being less abrasive and awkward than trump.
In other words, votes for Biden was more of anti trump votes rather than pro biden votes.
Less noticeable is Trump despite his eccentric style and failings almost won. It means the base support for his far right policies would probably hover around the 40+% regions. Very much close to the finishing line.
With such high base support from the opposing camp, biden would be under pressure and it leaves very little room for any left leaning policies.
4 years down the road, Biden must be able to attract the same high turnout ( when trump factor wasn't there anymore) if he wants to win the second term.
American politics will likely remain highly divisive and spiral down the path of highest bidder wins.
When comes to China, Biden Will likely seek to contain China's raise. This is the only area which he is agreeable with Trump.