I'm an ex-racer (20+ years ago) who was off the bike for 15 years, and have come back to riding at a moderately high level. The following insights are based on my own experiences. Others may see the world differently...

Crit racing for someone who is unfamiliar and/or uncomfortable riding fast in a tight group is generally a bad idea, and is more likely to end in a bad way. Pack riding at speed is a skill that can be learned on group rides, but learning on race day is not something I recommend. If you do decide to try crit racing, be aware that Masters categories (40+, 50+, etc.) aren't a slow pace in a group with guys like you (newbies). Especially in So Cal, expect that the field will include a lot of guys who have been racing for 20+ years, and may include a few ex-pros. The racing will be fast and hard. New crit racers generally start off in Cat 5 races, but these field tend to be filled with young guys whose bodies are much more tolerant to crashes . Bottom line: This is a tough age to start racing crits...but it can be done. I highly recommend finding some faster local group rides o build speed and fitness before dipping your toe in the crit pool.

As an older ex-crit monkey, who no longer wishes to compete in that arena, I'm finding gravel racing to be a good place for me right now. That said, I'm looking to participate, rather than compete. I did the Belgian Waffle Ride in San Marcos last April, and it was a fantastic experience. Next month is another event in Atascadero that I'm eagerly anticipating. Gravel racing is a very different kind of fitness. Being able to keep motoring for 5+ hours, and dealing with a wide variety of terrain, is a world apart from doing hot laps around a business park for 40+ minutes. My training focus is very little about max power, and tolerance for repeated high-intensity efforts, and more about endurance, climbing strength, and sustainable tempo pace. The atmosphere is relaxed and fun, but the "racing" is what you make of it.

I'm not going to comment about TTs other than to say they have never been something I've enjoyed.

My first racing was on MTBs (early 1990s). I would consider doing a MTB race again before a crit.

Again all this is IMO, YMMV.