Just about anything can be turned into a nerdly pursuit, a game of building a benchmark and then optimizing against it, if you want to. And when you look deeply at "how do people feel content with themselves", it's because they have actually pursued such a goal throughout different aspects of their lives. The social ladder looks singular, oppressive, because from the outside, it just looks like have/have-nots, when the actual thing of it has a great deal to do with how you use your personality and inclinations, which situations you engage with and which you bow out from, and where you choose to invest effort. Tinder is just one game to optimize for, and you can bow out of it and play a different one. It's not high school; you can make up some rules now.

For example, socialization is not really about "I have friends/I don't have friends". Interacting with a retail worker to get coffee is socializing. Talking to strangers at the bar is socializing. Going in for the date or job interview is also socializing. Different people are interested in different facets of these things. You can be a wallflower in one space and gregarious in another. And friends tend to not be characters in a story, conveniently falling into meetings; nor are they rational-expectations economic actors, optimizing all situations for maximum self-interest; they're more like cattle you have to round up to do anything with because they will just stay home like you if left to themselves, so you end up with a Venn diagram of friends for "A" and friends for "B" with minimal overlap, cause that's what you can get them for.

There are game players on Twitch who are quite good at the games they play and get lots of followers - ergo they are popular - but show minimal social ability. Their face is well-lit, but they grunt and swear and complain their way through every session and ignore their chat. Nobody is going to be charmed by what they are saying, but expressiveness tends to show through their gameplay, which can make up for a lot. And there are also streamers who hide behind an avatar, are not particularly exceptional at game-playing, but have a great ability to build stories and create situations that get their chat engaged. And there's no hope of quantifying these differences as a rank of overall quality as a person, but the fact that those differences do exist and neither is muted, undefined, expressionless, really does matter, and matters more than the particulars.

So - think about how you want to engage with people. Study that problem. Going to the gym, getting a style change, etc can help, but they're like subsets of the overall direction you're going in. Becoming a kind of person that you are not OK with is not going to help. Likewise you can get stuck in a rut because it looks like being dishonest in that sense is the "right" way, that there is only one way to be social and it's not your way; that usually afflicts the young because they observe other people pushing boundaries in ways that they aren't OK with, see negative stereotypes, and think "well, maybe this isn't for me" and write off their engagement before they really try. But, it's also a socially constructed phenomenon in the first place. Taking your inclinations and principles and polishing them up as best you can is a great path to becoming an Interesting Person.