Actually, we shouldn't focus only on the most popular crypto currencies, as they have already pumped and you are to wait for a drawdown to invest in them. But in addition to mainstream coins you can try something less popular or new, as coins with smaller marketing campaign can increase more significantly compared to those that are already in top, but consider risks please.
On 2021 only so I supposed those coins are new but like he said, most of those have already died since their purpose is already over. The main reason why they become popular is only due to hypes. I like what you said there, we shouldn't focus on who is popular or if who is new because their life span are usually shorter but you can try them if you a short term goer but for those that are a fan of long term hodling, they should look for the coins with real life use cases.
We are now in the 2022 and most of the popular coins are from gaming or metaverse however there are still old coins that are still popular, one of it of course is bitcoin.