Can't get my conditional to check input value for str or int and ignore if statement (Python 3.9)

Trying to write a simple if, elif statement. I prompt the user for an input and: if input is an int(), run the if seconds => statement and begin countdown. elif input is a str(), print to the user to input an int().

print("We're ready captain! How many seconds until launch?")

seconds = input()

isInputString = type(seconds) == str #yields True if seconds == str()

if isInputString == True: #tell the user to try again
    print("I need a number Captain!")
    seconds = input() #prompt a second input

else: #else it wasn't a str() and to proceed on with script
    pass

Currently the script will prompt for a second input even if a int() was entered.

Is this due to how I entered my if - else statement?

I feel like it should resort to else - pass if an int() is entered but it still prompts the 2nd branch input() even though isInputString == False.