Of course Norseman were the first Europeans to discover and colonise the Americas. However, the later rediscovery of the Americas in the late 15th century has had a much larger impact on global history than these early expeditions.

While Inuits weren't in Greenland yet (as they didn't exist as a culture at the time), there were definitely humans living in Greenland when the Vikings arrived. The Norse and natives (called Skrælings by the Norse) developed a relationship of sorts - sometimes they traded, sometimes they fought. They mostly fought.

Part of the reason why the Norsemen were unable to expand in North America, and at least a contributing factor of why they abandoned their colonies in Greenland, is because there were natives there. It was difficult to expand into Vinland and other parts of modern day Canada when the natives didn't want you there and were prepared and equipped to fight you off. Similarly in Greenland, the locals (named Skrælings by the Norse) were always in conflict with the Norse. Iceland didn't have a native population (maybe just some Irish monks), so exiled Norsemen could relatively easily settle there. It was difficult to be profitable and stable in places like Greenland when you're trying to get walrus ivory and farm all the while trying to fight off angry, well prepared, well adapted locals.

Edit: And maybe someone started taking the Norse legends a lot more seriously after Columbus's discovery - it's certainly possible. Or maybe someone asked an Icelander and they said "oh sure that place from the saga, it's just over there, can't miss it"

John Cabot (Giovanni Caboto) did indeed lead the first documented expedition to North America, however it has long been speculated that sailors already knew something was out there.

It is theorised that sailors from Bristol knew about the new world earlier in the 15th century, although there isn't any concrete evidence (to be fair, it's difficult to find sources about sailor gossip in the 1400s).
Sailors and fishermen were already travelling far into the Atlantic at this time, it doesn't seem too outlandish that some were swept far off-course and washed up in Newfoundland or similar...

Perhaps someone washed up there in the 1430s, which would explain this coin. Maybe they even made it back, but I suspect they didn't if they parted with such a valuable item.

We only know about Cabot because he was high profile enough to secure warrants from the King for his expeditions as well as funding from wealthy merchants. For my two cents, he wouldn't have been granted these without some level of proof that the new world was there.
To be fair, Columbus's expeditions had returned recently so central America and the Carribbean were known about. Maybe someone wondered how far north the New World went, but also maybe someone started taking those drunk Bristolian sailors a bit more seriously.

There are some reputable historians looking at this (see The Cabot Project), and there might even be evidence to support it. (Unfortunately an important and well regarded historian claimed to have evidence and was writing a book about it when she passed. In her will she said to destroy all her unpublished work, so the book and her claims never saw the light of day).
However, as a Bristolian myself, I like to think that we discovered the Americas ages before Columbus or Cabot and that they just stole the limelight.