Are there many kidney donors in the world?

Good Question. Well over 120, 000 in the us; about 6, 000 a year during the last few years. One would guess at least that many around the world. The numbers increase every year.
Yes. As many as there are living people; that doesn't mean everyone is a candidate based on their health history, nor are they willing participants. The short answer to your question is yes...But the factual answer is it depends on the individual needs and requirement of the person in need of the organ.