Congrats! You've reached a milestone few entrepreneurs do - you have paying customers!

More tactically:
1. If you have CAC < ACV for an initial trial that's a great sign of existing market demand. Especially if this is an unoptimised PPC campaign.
2a. You've not mentioned how long this experiment ran. If it was a few hours, it suggests that the market is significantly large. If it ran for a week, not as much.
2b. If you're paying $1.5 per click, that suggest low or no competition (depending on the segment, keywords, optimisation).
3. If you got your money back, and your COGS of the product are low, keep pumping at least the $500 back into PPC. There is no downside, and you will quickly find out what the limit is.
4. May be relevant for an angel investor (friends, family, fools) not institutional. The ticket size is low, churn is unknown, and market size is unclear.

There is a huge amount of work ahead of you in segmentation, targeting, to find adjacent segments, building a referral program, and understanding market scale.

But this is an awesome first step! I've helped multiple B2C products & marketplaces scale revenues 2-10X over 6 months, can help more over a call.