Someone that loves James Brown and Aretha Franklin as much as I do. That’s a Soul Mate.

Soulmates are people that are closer to you than others. Not on a personal level but a higher level, hence "soul mate".
Soulmates aren't necessarily your romantic partner. You have many soulmates, your parents, children, friends, oftentimes colleagues as well. And sometimes people who enter your life for a few minutes or days only.
They can still be soulmates, the encounter brings you something you need in your life to grow and evolve.

Often you've been together with your Soulmates in previous lives, so when you meet one you may immediately feel comfortable and even like "I know you?!" while you've never seen them before in your life.

So some are closer to you -like a partner and the ones you had-, children, parents, and others that aren't quite that close like a new person that enters your life for a shorter period of time.

There are other types of soul connections like the Twin Soul, Twin Flame, Twin Ray.
Different ballgame.
Especially Twin Soul can be quite chaotic, not necessarily an easy connection. You are closer with them than a Soulmate, so the highs are higher but the lows are also lower. You often mirror each other -through which you grow & learn- but in spite of the higher love it can also be way more confrontational.

You also have more than 1 Twin Soul but they're still not necessarily your partner although I do think it happens a lot that people get involved with one and then have a turbulent relationship.
These love relationships aren't easy, as I explained, and don't always last.

I'll leave it at that since the question was on 'Soulmates", not the rest.

I have experienced the same feelings once, and when in a deep relationship, it was very strange and mysterious.

It’s not just to be with someone, but to be with someone you can easily trust and believe in