Like others have mentioned here, the lack of dynamic samples in the bbcso discover doesn't really do the writing justice 😁
Re: some of the mixing things already mentioned, I've tend to find that you should be really conservative with using compression in orchestra music as it can kill the dynamics very easily and make the bass too loud and boomy.
A thing kinda adding to that, that came while listening the first time was during Where People Used To Be when the pizzicato basses first came in they were a bit too loud and kind of made them end up overpowering the other instruments and weakening the impact of the other percussion as they came in, but that's just slight nitpicking on my end 😉
If you are looking for other free orchestral sounds, orchestral tools recently released a free version of their berlin orchestra soundset called the Berlin Free Orchestra which might be a good addition alongside your bbcso discover and they have some other nice free sounds in their Sinefactory series of instruments, also there is the ProjectSam free orchestra that has some good stuff too.
If these are the first actual complete you've made, you should be really proud of what you've made! Lets just say, you don't want to hear my first ever complete tracks that I managed to make, since compared to these they are doo-doo 🤣
Good job!