How did early landing craft protect themselves?

What did those landing craft have for self-protection?

Not much in some cases; others carried light weapons such as machine guns, especially the dedicated support variants.

Early landing craft did not have uniform protection. Some carried little or nothing beyond their basic structure, while support variants mounted machine guns. Those armed derivatives were intended to suppress positions close to the beach and sometimes drove ashore to do so. Their survival therefore depended on nearby naval and air support as well as whatever weapons they carried themselves.