Was Columbus the second to find America?

First there were the Native Americans, who entered America about 18,000 years ago. Then there may have been Irish monks in about AD 700. Then there were definitely Norsemen in about AD 1000. Then there were probably Bristolian fishermen around AD 1480. Then there was Columbus in the Caribbean in AD 1492, but he didn't see the American mainland until several years later, by which time many Europeans had landed there. Columbus himself never recognised that he had found a 'new world', he tought he had seen part of China or the EAST Indes.