Welcome! Definitely go back to the General area and read all of the posts under "How did you choose"? This will give you some ideas to think about. This is a very personal decision and depends on how you want to live and personal preferences--there is no brand or RV that is one-size-fits-all. I think I would go a little newer than 1990s, if you can afford it. You might find a gem, but are more likely to find damage and a money pit in a really old RV.
I am very happy with my full-time for over four years choice of a 32' Class C. I also do not tow and do just fine. I mostly run errands and shop between campgrounds, but prefer to stay in one place several days. I also prefer state and federal campgrounds because there is more privacy and they are more scenic, and also because I never use the pool and am not interested in activities. My preferences. It hurts for me to kneel and I have very fragile kneecaps, so a walk around or "squeeze-around" bed was one of my requirements. I also often use a stool to sit on to hook up sewer hoses because I have vertigo often and get dizzy bending over, and I also need a wrench to tighten the water hose, so there is a solution for every physical problem!!!
A Class C is a good size for one person, at least for me. I have two big slides and have plenty of room. A motorhome is much easier to unhook and hook up, especially for things like dumping tanks if you prefer state and federal parks like I do. Being alone, I can take a shower and wash dishes each day and need to dump only once every three-five days. I just push a button to put my slides in, unhook electric and my water hose, and off I go!
Very fast and easy. With a trailer, you either have to shower in the campground shower rooms or you have to hook up a lot and drive to the dump, unless you want to stay in commercial campgrounds with full hookups.
I also thought I had to have levelers, but never got them. For one thing, my sites are level enough about 60-70% of the time. When I do have an un-level site, I just get out some 2 x 10" boards that are 24" long and place a couple under one set of tires (usually duallies) and drive up on them. Easy and cheap.
As far as age goes, I am 73, and started at age 69. I have met several ladies on the road who are older than I am, some into their 80s and they do just fine driving even really big rigs! So, where do you live? We forum members travel all over the place and are always happy to meet with a newcomer and show you our rigs and what works and does not work about them.