Samba have pretty flexible soles; it's part of what makes them so comfortable.

Some folks prefer a shoe with a stiffer sole, to keep the shoe sole from "folding" around the pedal. But that stiffness makes walking less comfortable.

If you prefer to cycle in soft-soled shoes, maybe consider a pedal with a larger platform? You can find decent, inexpensive pedals with large platforms; usually labeled for BMX or MTB.
Just make sure you get the correct spindle size; juvenile, some vintage, and some BMX bikes (with a 1-piece crank) use a smaller 1/2" spindle. You probably need a 9/16" spindle for your adult bike.