I was hoping to run Linux mint or another OS on it like a regular computer
The original “Raspbian” OS is basically Debian, a full Linux distribution, “like a regular computer”. Just not a very powerful one, even by 13 year-old standards…
Everything is on the SD card, and if you want to run alternative OSs you need to prepare the SD card on Mac or PC (or another Pi). Part of the appeal is that you can change OS just by swapping the SD card.
What you need to do is install the Raspberry Pi imager on your Mac:
Flash Raspbian to your SD card with the Raspberry Pi Imager, our brand new imaging utility. Download it free today!
www.raspberrypi.com
...and if you run this it will give you a menu of operating systems that you can run, even on a Raspberry Pi 1 - although TBH the choices for general purpose OS are pretty much Raspberry Pi OS, RISC OS, or Alpine Linux. But there's a bunch of dedicated OSs for everything from media players to retro gaming. I fondly remember RISC OS from back in the day (make sure you've got a 3-button mouse!), but not sure if I'd want to go back!
Pis are surprisingly viable for running Kodi or something to play playing videos stored on a NAS on a HD TV. However, a base Pi 1 may be pushing it, and ISTR that for the Pi 1 & 2 you had to buy a $5 unlock key for the MP4 decoder for some file formats.
Newer Pis are viable as basic desktop systems but the original is probably better dedicated to a single task (the advantage is that they rtake less power than the newer ones).
Main point of the Pi 1 was playing around and having fun (or mucking about with controlling hardware) - if you want a boring practical use then - as several people have already mentioned - there is PiHole (I have that running on a RasPi 2, but I thing a Raspi 1 would do it):
pi-hole.net