Hi! Thank you for trying a game! Without spoiling toooo much, I'll tell you there is a way to make the big blocks/smaller blocks interact to break the shields. I hope this helps!
I did realise the hitbox for the big block isn't properly set up to hurt the player when attacking after reading your comment, little oversight, I'll make sure to update that in a post-jam version once the rating period of the game jam we built this for is over, thank you!