I agree with Marc => Airtable to start without any doubt.
Also, SQL datasources are for the business plan (for the new pricing). And it needs a lot of knowledge to get things done.
If you generate some decent incomes from your Softr + Airtable MVP 
- Consider using Supabase (accessible with the Softr professional plan). Supabase is $25/month.
Not really a beginner database but very powerful. - Or consider going back to Xano