Yes there is a lot of sexism in the music industry still, although it's changing. The conductor is the authority - what he/she says, goes - so like in many fields, it has traditionally been harder for a woman to be accepted as 'the boss'. You need to follow what the conductor has decided, in terms of tempo, articulation, character, etc, whether you like it or not, you need to obey all their commands in rehearsal - they decide what bit is going to be rehearsed and how, and it's done until they're satisfied, etc., so they are very much in charge.
They also have a huge wealth of musical knowledge behind them that informs how they decide to approach a piece. Our conductor (amateur orchestra but with a professional conductor) is full of knowledge and stories about the composers, the pieces, the time period etc, how it all links together, and how that influences the piece and his interpretation of it. He knows so much about it all, and that's before you even get to the actual conducting bit! Conducting itself is hard, too - most pieces don't stay in one tempo, many have really complicated time signatures that change frequently - and if he doesn't make it clear exactly what is happening, people will make mistakes and the whole thing sounds awful and can fall apart. Much of the amazing bits of music come from the tension, the rests, the anticipation between chords, etc., - and if that goes wrong, the magic will be lost. It might sound 'ok' to a listener, all the right notes are there, but nothing more. There are huge differences between a good conductor who keeps the orchestra together, and a great conductor, who really makes magic. (And of course, a bad conductor, who can't even keep everyone together!).
It takes ages to learn to do it well. People can learn the basics of the arm movements - most music teachers can keep a choir together with straightforward beating, for example - but to conduct a whole orchestra is hard, and to really get your interpretation across, harder still.
The conductors I've known usually have played a couple of instruments seriously as children/youth, and spent a lot of time in youth orchestras, or choirs. At some point, they decide they're more interested in conducting, and may get a chance to try with school ensembles or at university. Playing chamber music can also help, as you're kind of all involved in keeping it together and seeing how things fit, even if there isn't one person in charge. Then if they are serious about doing it professionally, they would usually then study music. Some do a music degree on their instrument first and then decide to conduct later, others do conducting as their first study. I have met one conductor who is now very good who did kind of learn on the job, but he was already a professional musician and very talented.
conductors have to be good with people, too. To get the orchestra to do exactly what you want, you need to have a good rapport with them. You have to criticise constructively, sometimes repeatedly, keep them interested and on side, etc. - very much teamwork needed. So someone with excellent music skills can lack that people-side, and never really get to the top of their career. I know a conductor like this - he could be excellent, but he just puts everyone's back up, constantly.
There are lots of music concerts for children around (I suspect I know who the superman conductor was, and although that might not be the best performance to recommend, I think they are usually very good!), and many of them introduce the instruments and children can hear the different sounds etc. Many of them might be drawn to something in particular. Piano is always useful, regardless of which orchestral instrument someone tries as well. Some children find it easier to read only one line of music, so beginning on another instrument might be easier for them as you can make quicker progress. Some like faster results - string instruments can be quite slow to sound good, but are beautiful in the end - whereas brass can be faster to get to sound OK. Some take a lot of puff, which doesn't suit some children. Others tend to end up with more solo parts in orchestras, which doesn't suit some children. Others are happy being part of a large section. So loads of reasons to try different ones until you find the one that clicks.