While I would recommend Splatoon 2 as a great introduction to multiplayer shooter games, the game will be overshadowed by its upcoming sequel that is expected to release [in 2022](https://www.nintendo.com/games/detail/splatoon-3-switch/). While there is a single player campaign available, you would not be able to fully enjoy the online capabilities once the player base moves on to Splatoon 3. It is likely a good idea to just wait until the third game releases.
Nintendo Switch