Is it worth it?

Should I join the track team? I have never timed myself properly. I am very slow and I want to get better for my high school track team because it does look fun. I’m not sure how accurate the measure app on the iPhone is, but I used it to measure 50 meters. I got 10 seconds going slightly uphill and counting in my head…😅. I just calculated my 100 meters to be around 18-20 seconds. I don’t have a track near me that I can use and my neighborhood is a little weird. My high-school is small and there aren’t really any cuts I would say for teams, but I just don’t want to embarrass myself. Tryouts are in a week. Could I get faster? Should I join the team? I do want to get faster, so is there any way I can? I have a treadmill so yeah.