To be successful as a freelancer here on Fiverr, you should be offering skills that you do well, not just skills that are in demand. Every gig category on Fiverr has it’s own market, and there is demand for services in every market.
Figure out what YOU love to do, and what you are able to do well, and offer those skills as gigs here on Fiverr. If you want to be successful here, it is best that you are personally connected the services that you choose to offer.
Fiverr is not a get-rich-quick website. It is intended to be a catalog of skilled freelancers offering their skills to others who need them at a low or reasonable price.
Find what YOU love, and go from there.