The way the filibuster actually works is that you need a vote to close the debate before you have the vote on the bill, and
that vote requires 60 rather than 51, and
that makes some sense. Because if a bill is going to pass 97 to 3 and the proponents are satisfied they've heard enough discussion, the chances of you convincing 47 Senators to change their vote are pretty slim. But if the bill is only going to pass 51 to 49, there's a real chance you might be able to change the result if you had more time, and so the rules give the minority the ability to delay the vote if the vote is close enough.
Of course, since they can take as long as they want, that means in practice they can delay the vote indefinitely. But that doesn't seem substantially different than some committee being able to kill a bill by just never passing it through to the full Senate even if it would pass there. It's just another opportunity to prevent government action if there is insufficient consensus.
And "60 votes to end debate" and "60 votes to pass a bill" aren't the same thing, and therefore aren't superfluous. The Senate passes many, many bills by a vote of less than 60 to 40, because many Senators will vote to end debate on a bill they intend to vote against. The filibuster is a means for the minority party to moderate a bill that they generally don't support. If the majority party submits an extremist version of a bill, the minority threatens to filibuster it unless they replace it with a moderate version. Then they don't filibuster the moderate bill but still vote against it, and it passes along party lines with less than 60 votes.
Also notice that it doesn't take 60 votes to amend the Senate rules to eliminate the filibuster. If the majority wanted it enough, they could remove the rule and then pass whatever they wanted with 51 votes. But then so could the other party, the next time they're in the majority. There are enough Senators who don't want to see that happen the next time they're in the minority that there aren't 51 votes to change the rules. Even if there are 51 votes to pass a bill the other party is filibustering.