There have been attempts to use other contemporary English pronouns to stand-in as a true gender-neutral pronoun, given that English is lacking a commonly-accepted one for adult humans (non-humans and even babies can be referred to as 'it'). Examples of this include 'he/she', 'one', and the singular 'they'.
However, these can be confused with the contemporary pronouns which have been used as stand-ins, and they can at times be awkward to use. Other pronouns exist which can avoid this problem, such as 'thon', which seems to have historically picked up the most momentum, and was in the dictionary as recently as 1964!
Which are the most commonly used gender-neutral pronouns in English around the world today, to be used when referring back to an adult human, that aren't the same as other contemporary pronouns?