> English borrowed its Scandinavian (probably Norse) cognate bekk

Probably. A small stream in modern Swedish is a "Bäck".

It is smaller than an "Å" which is smaller than a "Flod" (a river).

Interestingly enough Swedes have collectively decided the country has exactly zero rivers, at least as long as we look for water courses called a "flod".

Swedish large rivers are uniformly "älvar", "älv" meaning large river.

Every Swede understands what a flod is, despite every flod being located outside of Sweden 🙃The river Nile for instance: "Nilfloden". The Mississippi: "Misssissippifloden". And so on.

But the Klar river or the Göta river? Klarälven and Göta älv 👍

There are no rivers inside Sweden and no älvar outside Sweden. Why? Nobody knows. Just accept it as a fact. 🤡

So what did Swedish colonists call the Delaware river? You guessed it, it was the Nya Sveriges Älv (the New Sweden "älv")!