Welcome to the forum
First, check out our
Retro forum—I assume most games mentioned there should run on your PC.
Second, check out
GOG—it's got hundreds of 'Good Old Games'.
Third, here's a list from my notes of 'Potato friendly' games—no idea offhand which ones might run on your spud, but check their system requirements on Steam:
Age of Empires 2 DE
Age of Mythology
Baba Is You
Besiege
Bioshock bundle
Blazing Chrome
Civ 4
C&C Remastered
Cuphead
Crysis / Warhead
Dead Space bundle
Don't Starve
Dorfromantik
Elder Scrolls 4 Oblivion
Elder Scrolls 5 Skyrim
Enter the Gungeon
Factorio
Fallout: New Vegas
Far Cry 3
Farming Sim 20xx
FTL: Faster Than Light
Hades
Halo MC bundle
Her Story
If On A Winter's Night, Four Travelers
Into the Breach
KotOR & Sith Lords
LA Noire
Minecraft
Moonlighter
Papers, Please
Plants v Zombies
Portal / 2
Power Wash Sim
Satisfactory
Slay the Spire
Sniper Elite 4
Spelunky
Spore
Stardew Valley
SupCom FA
TA Battle Sim
Terraria
The Binding of Isaac: Rebirth
The Talos Principle
The Turing Test
Truck Sims
Undertale
Untitled Goose Game
War Robots: Planet Defender
West of Loathing