Was it only Caleb and Joshua who entered the promised land?

Yes and no; mostly no.

The generation of the Israelites who left Egypt were made by God to tarry in the wilderness for forty years (Numbers ch.14). They all died in those 40 years, but not before they had all had children (Numbers ch.26). Those children all entered the Holy Land (Joshua ch.3-4).

Of the elder generation that had left Egypt and died in the wilderness, only Joshua and Calev survived. Plus the women and the entire tribe of Levi, none of whom died in the wilderness.