It's still difficult to see how to resolve this without seeing the raw data that you are passing into the Select actions and what expressions you are using in them to extract the data. Plus, what output you are after as an end result.
If you're just trying to extract values from an array of objects and have them as values in a single array, then you can do the following.
Example array of objects:
[
{
"Color": "Red"
},
{
"Color": "Green"
},
{
"Color": "Blue"
}
]
Output you are trying to achieve:
[
"Red",
"Green",
"Blue"
]
How to achieve this - using the following expression in the Map of the Select:
item()?['Color']

If you then wanted to join the values in the array you could use a Join as so:

This would give you:
Red,Green,Blue