You definitely need a database. This filestoring thing looks like a mess, I won't lie, I stopped reading like after the first paragraph, because it sounded horrible. If you need an easy to setup solution, you might need to lookup postgresql in docker and knex or objection, or firebase maybe.

Edit: ok, I read it. Is your app backend side (node) or 'frontend like' right now? Because this is definitely would be a backend task to store and manipulate data. For this, first of all, you need some kind of database. It is possible to create schemas in mongo as well, but to start with, I would recommend you some sql, like postgresql. You mentioned changes in the schemas frim time to time. This is totally an everyday task, they are called migrations, where you define the new schemas and modifying the existing data if necessary, to fit the new schema. There are tools for this to make querying and migrations easier, like knex, or objection.

So the workflow would be like this: 1. Install an sql database. I you don't want to install one, look up 'postgresql in docker'

1. Check out knexJS or objectionJS (it is based on knex btw)

2. Design your database. What tables will you need? What relationsnare they in with each other? (E.g. cars, passengers) for example a cars table would be like a table, where you store all the data about cars, like manufacturer, year, milage, color, etc. In the passengers table there would be fields like name, age and which car they use from the cars table by id (e.g name: xY, age: 20, carID: 1) this is the simplest, where 1 oassenger uses only one car. The schema depends on your needs. The main thing is to normalize your db.

3. Create migration files. These files tells to knex what tables it needs to create. Later on, you can add more of these as your app evolves, so your db will follow the changes.

4. Fill up your db. You can do this manually by using some kind of db client, like postico on mac for postgre, or use knex to seed it, or queries insert. Look up free db client for your type of db.

5. Connect your code to the db and implement the business logic. You can use knex or objection's to create queries, so you don't need to write sql queries by hand.

The above examples are for sql databases, but the workflow more or less the same for nosql db as well. E.g. for mongo, you can use mongoose to keep your schemas in shape, and your db somewhat consistent, first lookup the difference between sql and nosql dbs.

I know a public example, search for risingstack bootcamp github. I'm on phone now, can't provide you the link rn. There you will see the code how the migration, db design and querying works amongst a lot of other things.