But Germany had no realistic chance of matching British sea (surface ship) power. The clear lesson of WWI was that big gunships were all but useless but U-boats very effective.
I doubt that's the lesson they took away from WWI.
The lessons of WWI from a naval perspective are:
1.) An enemy with surface superiority can legally and effectively implement a blockade, thus gradually exacerbating supply problems even for a continental power like Germany.
2.) An enemy with a lot of submarines can try to implement a similar blockade but only with great difficulty and may ultimately fail, especially against the world's leading sea power.
3.) The Royal Navy can be tied down and limited to tactical victories by judicious use of a surface fleet.
Obviously having a superior fleet would be preferable, but it isn't possible, as you point out.
On the whole, though, the more pressing threat to the German regime in 1930 is domestic, not international, so spending more resources building up the navy isn't going to help matters there.
Hence, I would play for time by investing what I needed to keep a good corps of professional people in the navy and a progressive skill base in the design bureau, focus on more pressing matters, and hope that down the road more resources will be available for the navy.