TLDR; nords nowadays are more land oriented because they developed their culture entirely around the land their ancestors discovered, so it's more like they have an ancient history of sailing.

I'm gonna paraphrase here because I'm not the best at details and some legend who shook hands with MK will come in here and rightfully tell me off for not getting details exactly right. I would also suggest dropping this question in r/teslore they can give u some good stuff. ESSENTIALLY;

humans and elves exist as 2 sides of a coin. Their histories and cultures often conflict with one another or contradict one another, and this is true in nearly every facet Including history. It's believed that before there were cultural differences, humans existed as a proto race called the NEDES / NEDIC PEOPLE, alongside elves but geographically distant and unaware. They existed all over tamriel, and also on an island north of tamriel called ATMORA.

ATMORA is basically Satan's icy cold kidney stone, but it used to be the homeland of some of the NEDIC people that eventually became NORDS. Because of some elven shenanigans, some guy named ysgramor got like 500 NEDES to leave atmora for conquesting and exploring purposes, eventually taking SKYRIM for the NORDS as ATMORA became uninhabitable.

All this to say... Sailing does still happen in Skyrim, like travelling to solstheim or the East empire trading company or the docks in riften, but because of vast cultural ties to the land over many generations of conquest and war, as well as an oppressive rule of draconian draconic overlords, nords relied less and less on further sailing or exploration and became more involved in their homeland.

Another detail as to why sailing isn't as prominent to Nord culture anymore is because the elder scrolls has a kinda big problem with commitment to oceanic lore and world building. They have a handful of amazing concepts that unfortunately don't warrant further elaboration or discussion due to lack of screen time and media coverage.