It sounds mostly like you got yourself sorted out. I'm not in the SAA game, but by all accounts, it seems like you got a fair deal for a decent entry level gun. You can learn the ins and outs of the Single Action Army without risking harm to what one might call a 'collector grade' example.
It is disheartening to buy something and have it be less than what you were expecting, but as others have said, there is a charm to a well worn gun. These revolvers were working guns and tools, and people used them for that very purpose. Along with that, when things needed repaired or maintained, they did it themselves or went to the local shop. People weren't spending large sums of money to ship their gun to world famous restoration companies. They just did what needed to be done to keep it going, and as you can see, here it is today in your hands, still good to be shot.
While it's not a SAA, I shared a story recently about my first gun that I bought, which was a Detective Special. It was pretty worn out and had seen better days, but I did the same thing you did. I jumped and bought it at a 'fair' going rate without doing any research ahead. I was still happy with it as a shooter, but I'm sure I thought I could have done better.
What I just recently found out, as I requested an archives letter from Colt (which shows original specs & shipping details), was that my 'beater' revolver was shipped to the Philadelphia Police Department, where it was issued as a service weapon. While that's likely very different than the history of your gun, it taught me that my gun was a working gun too. Someone used it for a job, and it served its purpose. They weren't worried with how worn it was or what it looked like, which gave me a newfound appreciation for what I thought was a gun past its prime. Yours is the same way. You might not know who owned it before you had it, but do know that's it's packed full of history and life, especially if it is from 1899. That gun has experienced a lot.