I'm sure that, given a large sample size, I'll be able to find a few people that are like me, but I don't really know where to go, whether physically or online. Essentially, I am at a dead end in this respect.
I mostly talk to people if one of us needs something, but not much besides that.
Where do I go to meet interesting people and start afresh?
"... meet interesting people and start afresh?" - A simple MVP approach might be to make a list of places/things you wouldn't normally go/do and rate the viability of each? Take a stab at things in the top 10% of your viability list?
Consider that in performing an experiment where you meet new different people, you're quite likely to come out the other side a little different as the person you were going in.
I've spent the better part of my adult life moving around etc, different cities, regions etc and making new friends is as systematic of an endeavor as any other tech problem you might be trying to solve. Consider approaching it from that angle.
Good Luck - now go do some things you wouldn't normally do!
EDIT: Above all, never forget that your life will quickly start to resemble the things you spend the majority of your time thinking about. If you spend your time systematizing the process of starting fresh and meeting new people it will happen as certainly as spending enough time thinking about X will eventually make you a student of X and possibly even an expert of X.
* A heart surgeon in residency
* A guy who does flooring / carpentry
* A physics professor
* A bass violin player
* An actuary
* A piano tuner
* A computational biology post-doc
We have fun conversations and other than a foundational worldview alignment tend to have very different perspectives on politics/life choices/etc. Our church could be more diverse in many different ways but it certainly is diverse socioeconomically and I have benefited enormously because of these friendships.
Nowadays, I would recommend looking into gardening, beekeeping, or homesteading groups in your area. As food prices go up, there has been a surge in these. I meet a lot of interesting people in these kind of meetups.
I'm betting you think most people aren't that interesting. You might be surprised to find out you're the uninteresting one. Learn to Salsa dance, learn to admire art, learn to cook. Essentially, learn what other people like, then become proficient in those things. Host a poker night, cook a 7 course meal for people you know, join habitat for humanity, become a transport pilot on the weekends. Learn to smoke meat, then host people at your place.
I'm guessing you are only interested in super niche things that are mostly solo affairs. You're annoyed because no one wants to build database backends with you. Think about it from the other persons perspective. Find things to love about activities that they like.
I personally like people who are competitive and really pushing themselves. Crossfit, Jiu Jitsu, startup/finance events, events at math departments in universities, angel investor groups.
In my experience, the older people who play trivia at bars (late 40s/50s+) are interesting.
Even if you're younger, Introduce yourself and ask if you can join their team that day.
If you're interesting and can carry a good comversation, chances are they'll let you join their team again, and it could be the beginning of a friendship.
I almost never know the trivia answers, but that didn't matter because they like me.
Working with NPOs will expose you to some of the most interesting people on Earth.
Good luck!
Have you tried to speak to people just to chat and see how each other is doing?
What about a club or activity you can enjoy with other people?
IMHO closeness happens from harmonious character, from personality (mainly extroversion), not interests.