A left thumb suggestion
The goal here is for you to play the right thumb’s two-note chord part more or less as written, and to invent your own left thumb part. You may have already been successful with this, or you might feel you have no clue of what to do. If the latter is true, here is a left thumb suggestion for you.
Notice how the left thumb and right thumb do not overlap. The left thumb plays the same part in measures 1, 2, and 3. In going from the high E to the middle A on the left side, you can slide off the upper row tine to accomplish this smoothly. The left thumb part in measure 4 switches the notes around and plays the B for the first time. Why B? Because it is part of the E chord that was partially laid out by the right thumb in the first part of measure 4.
I hope this gives you some more ideas for how the left thumb can dance among those notes in answer to the right thumb’s part.