The book of Vayikra ends with the various ways one can make gifts to the Tabernacle, Temple. These include self-valuations. I donate my value on the open market to the Temple. Obviously some preferred to give this monetary equivalent rather than animals or birds.
When new look at the Torah we might find the valuations difficult to understand. A male from 20 to 60 was 50 silver shekels. A woman of the same age was 30 silver shekels. A male from 5 to 20 was 20 Shekels and a female 10 shekels. And from one month to five years 5 shekels for a male and 3 shekels for a female. From sixty upwards 15 for a male and 10 for a female.
You could change your mind and ask for things back that you gave. But then to redeem them you had to add a fifth as a penalty, on to the original value.
Can it be that all this valuation was based on capacity for hard work? That might explain why females are valued less. But it doesn’t explain how a child from one month can be considered a worker. And why should we think an eighteen-year-old cannot work at least as hard as a twenty-year-old or indeed a fifty-nine-year-old? And nowadays anyway we would value brain power over brawn. In our society women often hold higher and more demanding positions than men.
Clearly this was an accepted form of religious devotion and not unlike when we make donations to synagogues when we often, illogically give multiples of 18 just because 18 has the same numerical value as the Hebrew for Life.
None of the explanations I have come across satisfies me. Sometimes we are left with questions.