Dogmax, I'd be careful relying on the advice in that link if I were you. I think the advice is aimed at authors of books and articles etc, rather than songwriters, so quite a lot of it is focussed on the "fair use" defence in the context of quoting someone else's material in your book/article. I don't think that defence would work where you're using another song's lyrics in your song, because you're not doing it for the purpose of criticism / comment / scholarship / news reporting, or even acknowledging the source.
I did a little googling... The singer/songwriter Tom McRae has a song "Walking 2 Hawaii" from a 2003 album which starts with the lyric, "Falling feels like flying until you hit the ground". The Jeff Bridges song "Fallin & Flyin" seems to have been published in 2010, so I guess either the writers/publishers of "Fallin & Flyin" got permission from Tom McRae, or they came up with their lyric without ever having heard Tom McRae's song, or they decided theirs was enough different that it wasn't an infringement.
If your lyric was written without ever having heard a previous song with that lyric then it's not a copy and so is not an infringement - Jane would own her own copyright in it. The problem is of course that the other songs are already published so it could be difficult to prove that she'd never heard them.
The safest bet would be to change the lyric enough that it is clearly not copied.
Having said that, it's only ever going to be a problem if you ever start making money from that song, because otherwise there'd be zero point in the copyright holder suing you. So if you're not expecting to make money, I probably wouldn't worry all that much about someone suing the pants off you!
It's then more of a moral question of whether you are acknowledging the original author of that line or not. If your line was taken from another author's work rather than being written as an original idea by Jane then the original author has a moral right to be identified. If you think about it from the other side, if you ever saw that someone else had used your lyric without your permission and without acknowledging you, knowing that they'd seen your lyric first, you'd rightfully be miffed (even if you probably wouldn't be considering a lawsuit!)
But like I said, if Jane wrote the lyric without having heard it somewhere else, then it's hers and she doesn't have a moral obligation to acknowledge anyone. Then it'd only be if you start making money that you'd need to start worrying about protecting yourselves from the possibility of being sued by someone who thinks they might be able to claim an infringement.