The individual letters would all have to be strings if that string “Hello” were to be pieced out into what would be now be stored as a list [“H”, “e”, “l”, “l”, “o”], and no longer as a string. Because to begin with, your [H, e, l, l, o] wouldn't be recognised by Python. Let's check the type; it will produce an error…
print(type([H, e, l, l, o]))
#OUTPUT (Error)
NameError: name 'H' is not defined
If those letters were say numbers or booleans, then they'd be recognised. E.g. [1, 2, 3, 4, 5]
So from your string “Hello”, what you could do is to piece it out into a list with a list() casting…
thestring = "Hello"
thelist = list(thestring)
print(thelist)
#OUTPUT
['H', 'e', 'l', 'l', 'o']
If you want your string back, as in getting back a string form from thelist, that'd be yet another story, such as using the .join()…
thelist = ['H', 'e', 'l', 'l', 'o']
thestringback = "".join(thelist)
print(thestringback)
#OUTPUT
Hello
print(type(thestringback))
<class 'str'>