As @cscharff replied, missing A or CNAME record.
In case you do not know how to add a new DNS record at Cloudflare, kindly see the steps in the article below:
There could be one more issue related to HTTPS, in case of SSL certificate, but as we say “first things first”, fix the DNS record, then we can help you with more if needed in case
Kindly, just to note, check if in case you have
domain forwarding feature enabled at your Namecheap interface (which can also cause some issues related to the few topics other people posted having Namecheap domain and Cloudflare in combination).