AoE2:DE has most single player content from all games.
you can try to any steam game and ask automatic refund if playtime is under 2hrs if game is not playable.
you need low graphics to minimum for DEs for sure.
There is AoE2: ~~HD~~ (2013) on steam too which will run better and may be good enough for you too if you just want to get into AoE singleplayer, you will miss newest improvements and campaigns and need to pay for DLCs included in DE base game though(bad value compared to DE but if it is what works that will do well enough).
AoE3 (2007) is also similarly okey choice for someone who cannot run DE version of that game as DE does not add much new single player content and some campaign changes are controversial.
There is also AoEO which can be played for free and has ton of single player content (solo or co-op) although that game has no deeper story apart quest descriptions whatsoever.
I would not recommend AoE1 or AoE4 for single player atm, AoE1 is being moved to be part AoE2:DE later this year so singleplayer content will likely be playable in aoe2 then and then AoE4 doesn’t have that much single player content coompared to other games yet and many current mission are a bit dull or repetitive.
There is new AoM remaster similar to DEs coming so i don’t recommend getting AoM especially when steam EE version is not that well received.
Probably start from AoE2 DE so you don’t need to look for new singleplayer content for long time