According to the comics, films, animated tv shows and live tv shows,
the question is this. This is also a factual scientific question
of an old 50s made-up character:
If Superman was born as part alien from the planet Krypton, then how
did he came to be made of beam/metal of some kind, even though he
crashed onto the planet earth through the space and clouds with the
covered escaped pod?

Superman was made of flesh not metal, what gave Superman his powers
was the power of a yellow star our Sun. The idea went something like
this, a normal midlife star is yellow as it ages it expands becomes
weaker and emits a reddish light were it gets the name red star. A
yellow star being younger and stronger would impart more strength on
to those that it iluminated than a red star would. Since Superman had
evolved to get his powers from a weaker red star a stronger yellow
star would give him that much more power.

From DCcomics website;

That Kent is no more than a mask for Superman is shown clearly in the
brief origin story, consuming less than a full page, that would be
expanded and elaborated with each retelling over the years. In the
original version, a nameless scientist on a nameless planet being
"destroyed by old age" puts his infant son in a spaceship bound for
Earth. The baby is found and taken to an orphanage, where his strength
amazes doctors. Reaching maturity, he dons the Superman costume and
takes a reporter's job as Clark Kent. No explanation is given for his
human name, or for the way the authorities kept his powers secret for
so many years.

You can read the whole story at http://www.dccomics.com/features/sm60/