I may have figured out what's wrong. I'm not certain how it happened, but I think your mod folder path is messed up.
If you are able to start the game and get to the main screen, then press "Mods" to open the mod panel, click the button above "Close" with a file path in it, and navigate to the mod folder. Either press "Select This Folder" if you can see the "mods" folder highlighted, or press "Select Current Folder" if you navigated inside the "mods" folder. The terminal that shows errors will show the path you chose and it should end with "/AppData/Roaming/Strive/mods". Press "Close" and "Exit", then restart the game. If I'm right the first 3 errors should go away, maybe even the last error if we're lucky.
Finding "Mansion.gd" will only help if you have added mods to your current game, and that can get messy.
"Mansion.gd" is a core game file that has been around since at least 523a(earliest version I have) and probably much longer. Make sure you are looking in the right set of folders. The saves, mods, and portraits are in the user's Appdata. Core game files such as ".gd" scripts are located in the same folder as the executable file. If you downloaded the zip, then it will be where you extracted the files to. If you used the itch.io app, then I recommend a OS file search for "Strive", "newsexsystem", or "groupselectpanel".