The elements come from one of three sources. The first source was the BIG BANG that created the Universe 14 billion years ago.
When the big bang occurred, the elementary particles initially were too hot to make any stable atoms... but after a few thousand years, when things cooled down a lot, Hydrogen and Helium got made. The ratio was about 1 He for every 4 H atoms. This is
called RIMORDIAL NUCLEOSYNTHESIS.
Then for elements from He to Fe: these elements are made on the interior of BIG stars (bigger than sun). They are stored there until the stars begin to die. At that point they become unstable and shed a lot of mass... they feed elements from Lithium (Li) to Fe iron into the interstellar medium from which new
Finally for elements from Iron (Fe) to Uranium (U, these elements get made
during rare events called supernovae. This is when a really massive star ends its life not in a mild way but in a gigantic explosion. During the few seconds of the SN explosion, all the elements more massive than iron and going all the way up to Uranium (and beyond), get made and spread out into the interstellar medium.
So ponder this:
the Fe in your blood was at some point many, many billions of years ago in the center of a star that has since then ceased to exist.