In addition to the
ずっと used to mean 'always', or 'non-stop', this
adverb may also convey that one thing is 'by far (A)', or 'much more (A)' than something else. In these phrases,
ずっと usually comes at the beginning of the sentence, before some form of comparison will be made between (A) and (B).
さっき見（み）た鳥（とり）よりずっと大（おお）きかったよ！
It was much bigger than the bird we saw earlier.
それよりずっと昔（むかし）だよ。
It was way more before that. (That happened way before that)
Although
ずっと as 'ever since', or 'always' may seem quite different to
ずっと as 'way more', or 'by far', the literal meanings are actually exactly the same. In all cases,
ずっと simply highlights 'an extremely big interval'.
ずっと運動（うんどう）していなかったから体（からだ）が全然（ぜんぜん）動（うご）かない。
I haven't exercised for an extremely long interval, so my body does not move at all.
そんな変（へん）な奴（やつ）よりこっちの方（ほう）がずっとすごいよ！
This one is so much better by a lot, compared to that weird thing!