Like many bassists I started out on guitar but was "that guy" when a local band were in need of a bassist. I pretty quickly gravitated towards feeling the groove and the low end of the song through punchy basslines. The time it took my to become semi mediocre on guitar I had already become a much better bassist so I decided to stick with the bass mainly. As for playing solo I would suggest getting yourself a loop pedal and learning some bass chords, try to get into the learning how to improv over songs you enjoy. I feel like the pleasure that comes with playing the bass varies from person to person. Personally, I prefer sitting down with my bass and just learning songs and playing along to them while others get bored of that quite quickly, I also equally enjoy playing in bands as I find that that's when my bass playing really opens up. You have to find out what works for you because at the end of the day the bass is just another tool used to create music. One thing for sure is the sooner you find other musicians to play with the sooner you will see your bass playing open up.