@Cangley11
Out of the 20 legends, Lifeline is the overall 8th most popular pick which includes casual lobbies + ranked at all elos. This makes her even more popular than Bangalore, Horizon and GIbbie for instance. In high elo ranked (Diamond to Predator) she is 11-12th most popular pick. And we know that she has 0% pick rate in competitive pro play like so many other legends, since only like 5-6 legends are viable in their comps and the way they play the game.
So I think "everyone knows" is a bit of an overstatement.. Lifeline is a viable legend but not top pick. But the thing with Lifeline is that her kits effectiveness strongly depends on your team playing around it, which makes her quite bad when playing with randoms (especially since 4/5 randoms leave as soon as they get knocked) .For instance, playing with a Pathfinder and a Wraith who plays super aggressive and uncoordinated can literally render Lifelines kit useless. But with the right team of premades who understands how to utilize a Lifeline, her kit can become super strong
Another thing I think many people are mistaken about Lifeline is that they think she can be played as a "support" or "healer" like in MOBAs or games like Overwatch, i.e that your primary mission in a fight is to literally stay behind and do nothing until a teammate dies and need a revive =). So often I see player with low fighting skill maining Lifeline because of this. So if you play Lifeline as this, you will for sure have a hard time winning since her kit will in no way compensate for leaving your teammates fighting 2v3 all the time. On the contrary, I think Lifelines need to be very good fighters. As a semi Lifeline main, I think its my job to also cover and fight anyone who pushes the revive.
Btw, what is a heirloom weapon?