Really Neat concept game. Cool!
I like the board and everything is compact from a world-view.
I like the simple system of scavenging for gold and having to eat to survive.
I think this game could use some very minor adjustments to make it much more playable, and it's essentially very well made and thoughtful, which is the other reason why I'm able to give you so many comments! Which is awesome.
1) Maybe distribution of spawns could be adjusted. It's so random now based on our initial speed, that nearly all games end in death. It's a little too heavily based on luck. there are many game instances where only a single coin and food spawn on my continent before I die, so there is literally no way to beat the game most times. Either like 5% to 10% more spawns, or they stay for just like a second or 2 longer.
2) You could keep all your sprites the same size, and easily make your game board world 20% larger, adding a bit more challenge to the later parts of the games.
3) The "store" menu could use a little work, it's very inconvenient to have to use that tiny tiny scroll box to check through the store items, especially since the game is timed. Ideally, since your actual map only takes up half your game screen, you can tweak your store interface to get everything we can actually buy (4 categories) on the left side of the screen. I think you could easily make all the extra large store sprites half their size and eliminate the scroll bar completely, making your game much much cleaner.
4) Your specific game would fare better with a music and sfx toggle bottom on one of the corners instead of a sub directory of the main menu.
5) The game feels pretty serious right now based on the music, there's not any kind of humorous undertones. I'd like to suggest carrying that out. For example, if the player dies in the snowy areas but doesn't have the mount, you could say, "You have perished from the cold after 'x' days of wandering. Try domesticating arctic creatures before venturing too far from the shore"
OR if the player dies on the starter island without buying the raft "You have perished from starvation after 'x' days of aimless wandering. Perhaps a raft could help you."
6) I'd recommend adding a restart or "try again" button when you die.
7) The spawn rates don't seem to be as high further away from the starting continent for some reason. I find myself staying around the starter island because of this. Might want to tweak spawn values further away from the start. It's one thing if I'm just making poor use of what I've bought, it's another thing to go an entire health bar without food spawning anywhere remote to you. It doesn't happen everytime, just MOST of the time, which means it's a hair too random.
8) Minor comment since your world is in your start screen. Maybe it would be cleaner if you didn't have to fade to black, your "person" just sort of spawned on the world that is already there, the world stays in place, and the menu fades out while the store icons fade in.
9) After you've purchased the final upgrades they stay in the store. I think they should either fade to nearly completely transparent, go away complete, say upgrade complete, out of stock, extinct, something in line with your game theme to make it more clear that there's no further upgrades.
10) After playing a couple times, there's not any ending. You can get all upgrades and race across the land and sea to still survive and get coins, but that's it. Maybe figure out a way to work in an ending.
What I personally think might be an interesting way to go is that there are forests in the grassland, mountains in the snow, plateaus in the hotlands, and deep water in the ocean that all of which are impassible without the final upgrade. This could add an extra layer of depth and strategy to your game pretty close to it's current form. I would call this being more inwardly focused. The other way to go, would be outward, when you purchase all the upgrades, your planet gets smaller the store repopulates, and you can start mining asteroids and the moon just outside the planet. Sort of nomad of the earth, to nomad of space, to nomad of the stars!
I know I'm getting kind of crazy here, but I think your game really lends itself to going in a multiple possible directions that could all be super fun. This means you have a great base platform and ideas right now! It's a wonderful start to what is a short charming little game. I hope you take it beyond the game jam version and really run with it.
Good Luck!!