>>718813371
don't listen to these anons, pirate WAW, BO1 or BO2, and play maps to try things out. Activision prices shit insanely high, and given these are older CoDs everything is still sold in overpriced map packs. If you like it then try getting on Plutonium servers and playing with others, then if you're all in pick up BO3.
YMMV after BO3, BO4 is fantastic if it's particular style is what you're looking for, Cold War was an intentional huge simplification which I personally think had good ideas but needed more execution but the maps are pretty dull, Vanguard I haven't played, MWZ was kinda cool imo but also was skinnerbox progression design which bored me, BO6 is CW again but better maps however the point economy is brutal, and BO7 looks to be more BO6.
*If* you get sucked into the story/lore, just know the mode is on it's 3rd, perhaps 4th creative vision. It's on Bungie to 343 lore rules if you get that, so just don't get too frustrated.