It's pretty clear that the "founding fathers" did not intend for "speech" as in "freedom of" to refer to money. And corporations, which were not mentioned in the Constitution, were later defined as "artificial persons," as contrated with "natural person" (aka human beings).

Unfortunately, the writers of the 14th Amendmet neglected to include the word "natural" before the word "person," thus opening up the possibility of such non-originalist judicial interpretations as "corporations are people & thus entitled to all the rights of natural persons."