Thanks for your reply!

I know 30 years isn't a lot of time but there is a reason for it. I didn't want to bring up the setting of my campaign but I could shed some more light into it in order to give more context.

It's set 30 years after the dreaded Spellplague which is the reason why magic doesn't work properly anymore. It caused the lands of all realities to literally erupt and break. In this case so bad that most of the major cities, villages and ruling classes cannot do anything and civilizations collapse. With blue firestorms burning every hamlet and forest, and chaos waves causing earthquakes, it becomes very difficult for the remaining people to survive. People have died, wizards have gone mad and/or vanished, and many races and magical beings have vanished for mysterious reasons (or randomly appeared, such as the Dragonborns!). Gods no longer answer prayers either.

So I thought 30 years of misery (barbarism, lack of food and water due to random burning farms, disrupted trade, etc), it could be considered a long time for humans. And sure, it's still not a long time for elves or dwarves but even they cannot ignore their crumbling mines, burning forest or the rise of monsters. Even they would be affected; especially if no magic can solve the problem. Although compared to the short-lived humans, they could be looking at the bigger picture and understand the long-term problem better.
So 30 years later, the hero party emerged and can, hopefully, help to solve it. :)

The effects of the Spellplague has diminished quite enough for civilizations to build up again but there are rampant problem with taking lands and maintaining order from brigands and self-proclaimed sorcerer kings who wield magic people now fear. The firestorm still rampages even though the source have been fixed and nobody knows why. The gods (and ambitious patrons) are struggling to reconnect but are also coming back. Magic works again but only for some. Old wizards (such as elves) cannot wield it anymore for unknown reason.

But yeah, now thinking about it, maybe 30 years is too little time to make any technological advancements; especially during post-apocalyptic living conditions in medieval time... Just thought maybe it made sense since magic can no longer solve every, single problem anymore which it used to do 31 years ago. :) It's not meant to be a big theme anyway so I don't feel I need to add more hundred of years. I am just trying to get a better understanding of the tech level and health in a normal setting and to adapt.