Not everything about a winning campaign is good. Not everything about a losing campaign is bad. This is what makes the last U.S. presidential election particularly interesting. For several days, we did not know who will ultimately win so we didn't immediately jump to conclusions about the campaigns as is otherwise usually being done on election night. Most pundits assumed that Joe Biden will win, but we didn't know for sure, let alone by what margin.
Personally, I think that it was actually more Donald Trump losing the election rather than Joe Biden winning it. In 2016, Trump benefited from the electoral college and got elected with a minority of the vote, only to spend much of his time in office alienating the majority who did not vote for him. And still, without the mismanagement on covid-19, he might have won reelection. Remember that when it was all said and done, respectively all votes were counted, 43'000 votes in three states made the difference.
So yes, the Biden campaign was definitely not the beginning of a new youth movement. He did not deliver great speeches and his debate performance was mediocre at best. This being said, the campaign did some things really well. Running a campaign is very much about drawing contrast, and the Biden campaign consistently did show contrast on the corona issue – both in style and substance. The Biden campaign had a very clear targeting strategy regarding the all-important electoral map, carried it out with discipline, and delivered. Democrats were also great in moving from getting out the vote to take home delivery of the vote. And Biden himself was smart enough to hold back and stay quiet during much of the summer, letting Trump self-destruct.