It's unfortunate that David Lowe's death record does not state his parents' names. Circumstantial evidence suggests, however, that William and Mary Lowe are indeed his parents.
In 1860 his wife Mareda is in Green County, Wisconsin. Per Find-a-Grave she married David Lowe in 1869. 1870 census not yet found, but in 1875 she's in Kansas with David Lowe and her children Jacob, Mary, Abigail, Harriett, Charlotte, and Elora Rosetta (Canfield surname) and also with their daughter Anna Lowe b ca 1871 in Iowa.
In 1850 we found a David Lowe of the right age to be Mareda's husband, living in Green County, Wisconsin. 1860 census for him not yet found, but his mother and sibs are in Monroe County, Wisconsin, and we found a marriage record in Monroe County, Wisconsin, for David Lowe and Hannah Cleveland.
In other words, the records posted put David Lowe and Mareda in approximately the right place at conceivably the right time to get married. And in the records posted, David Lowe's parents are William and Mary. There's not proof here, but at least these records tell more about where to look for proofs.
The Find-a-Grave creator seems to have the marriage record for David and Mareda, which may state his parents' names. So that's worth an email. And for the marriage to Hannah, the link for the marriage record I posted lets you order the original of that.
The U.S. Burial Registers, Military Posts and National Cemeteries say that the David Lowe who died in 1911 in Los Angeles, California, served in the 10th Wisconsin infantry in the Civil War. Los Angeles City Directory shows David and Mareda Lowe. His son George W Lowe appears in Los Angeles with children born in Wisconsin and Minnesota. These records among additional clues tie the family in California to the family in the records in Wisconsin.
The death records for David Lowe's parents, if they were William and Mary as we suspect, will perhaps tell more about them and should be searched. You also may be able to find obits for them.
Ditto for David's siblings. Their marriage records, death records, and obits may tell more about the parents. Again, if David does belong to the William and Mary family we found in Mount Pleasant, Wisconsin, the children of the family are (as shown in the 1850 census):
Benjamin Lowe born about 1832 Joseph P Lowe born about 1834 David Lowe born about 1836 Sarah born about 1838 William Lowe born about 1840 John C F Lowe born about 1843 Cyrus Lowe born about 1845 Mary E Lowe born about 1849
I neglected to post the place of birth with those sibs so one would start by fetching that info for them.
David's approx date of birth might be more accurate in the 1850 census record than the dob in later records in Los Angeles, when he was in a care-giving institution. Also he could have lied about his age on military records, and made himself a little older, and that is the dob they are using. And anyway, the discrepancy in his dob in the records falls within the normal range of discrepancies for genealogy records.