So, as we all know, the bus is broken when we first arrive in town, and the bus driver Pam, is unemployed as a result. We are able to fix the bus and put Pam back to work, after which Lewis will say that it had been dormant for "decades".

There is no way that bus had been broken for 20-30 years though. First of all, that would mean Pam had been unemployed for that long, essentially Penny's entire life. I dont see how that could be the case.

Second, if the bus had been sitting there for 30 years, it would be in way worse shape. The bus does not appear visibly decayed, like say the community center does, suggesting it has been in disrepair for less time the the CC, and considering most adult characters seem to have fond memories of the CC, I find it hard to believe the CC had even been abandoned for 30 years

Third, Sandy. Sandy is delighted to see the bus back up and running, saying she almost went out of business with it not running. How could that be if the bus had been broken with 20-30 years. She doesnt look old enough to have been running that business for 20+ years. She is also friends with Emily. Sure, they could just be online friends/Pen pals, but it still seems weird.

I think its reasonable to assume the bus had been broken for 2-5 years. I think thats pretty consistent with available evidence outside of Lewis's line.

However, what if we assume that Lewis is right, its been 20+ years, how could that possibly be true?
Well... we know a year in Stardew Valley is 4 seasons of 28 days each, 112 days total. What if that isnt an abstraction? What if years are literally shorter, but people and things age at the same rate as in the real world?
Think about it, you can play for 10 years and the kids dont get visibly older...in fact, no one does. What if thats because 1 of OUR years, is actually 3.25 of their years? If we take that to be true, then the 20-30 years the bus has been broken for, translates to 6 to 9 of our years, longer then I estimated, but much more inline with other available evidence. It also explains why no one ages, I cant speak for everyone but I usually play a farm for 3-5 in game years, well no wonder no one seems much older, they have only aged about 1-1.5 actual years.

It explains EVERYTHING :P