let me tell you about the intermediate value theorem
take a graph with no gaps ("continuous function"), and pick start and end points (a to b). doesn't matter what they are. just pick some horizontal chunk of the graph.
your start and end points obviously correspond to some values on the graph (f(a) and f(b)). if we say the graph is a timeline, you can think of this as starting at time a with a value of f(a), time passing, and ending up with a value of f(b) by the time it's b.
the intermediate value theorem says that during your journey, you had to pass through every value between f(a) and f(b) at least once.
for example, say the graph is of your weight. you start out at 180 pounds and end up at 150 pounds. (it doesn't even matter what a and b are!) no matter how crazy the part in the middle was, how much you rebounded or dropped below 150 or over 180, at some point you weighed 151 pounds. and 152 pounds. and 153 pounds. and 167.983 pounds. even for just a moment, it happened once.
sounds super obvious? ho ho.
i am pretty bad at art. my doodles are terribly embarrassing, to the point that it's hard to even keep trying. i look at mel and she is amazing. wow! how can i ever get that good? it is clearly impossible.
let us pretend briefly that "art talent" is something measurable enough to be put on a graph
everyone starts at zero. a baby can't draw worth jack. so mel was at zero art skill at some point in the past (i.e. worse than me), and is way better than me now. so my current ability is somewhere between those extremes.
by the intermediate value theorem, at some point, mel had exactly as much art skill as i have right now. and, clearly, she managed to get from that point to where she is now.