We are absolutely swimming in American culture! Like I said, fish are unaware of the water they swim in. It starts right from birth: For the past 7 decades or so, most Americans are born in hospitals. Not so in MANY other cultures. Baby boys are generally circumcised, Jewish or not. They used to be mostly bottle-fed, but most are not these days. Their mothers usually take maternity leave for some months but the length of time has shrunk from forever to a few months. All of these are cultural norms.
Babies are often christened or baptized. They have God Parents. Their mothers had baby showers. All cultural norms, not present in most other cultures. Children have constant supervision. They start school at 5 or 6, and attend until they are 17 or 18. They have chores, but few jobs until they are teens, but usually have allowances. Used to be only the children of the rich attended college, but in the last few decades there has been a lot more inclusivity. Used to be the only way poor kids could attend was by scholarship, but student loans are now the norm.
Young people have several relationships, mostly with the opposite sex before marriage. 70 years ago, homosexuality was criminal in most places, but that has become a cultural norm mostly. When young people do marry, it is mostly for love (not arranged marriage), and most couples have children after a few years. Unmarried procreation was cultural anathema some decades past, but more accepted now.
Most Americans have a vaguely Christian heritage, though fewer and fewer attend regular services or claim a particular church membership. This is VERY different from many other cultures. Some Americans have a Jewish heritage, but again there are a very wide variety of Jewish traditions, from Orthodox to atheist.
Americans mostly have expectations their medical care will be through insurance, government programs for the poor, or self-financed. This is very different from most other cultures where either single-payer of no health care at all is expected.
American couples have a high divorce rate. They don't have mistresses, but do have secret affairs. There are certain expectations for child custody and child support.
Work has a whole set of cultural expectations and many of those have become legal requirements. The list is long.
Almost universally, we expect Medicare at 65, and Social Security at 62-70 and for the rest of your life. When we die, we expect funerals, caskets, embalming, burial in a cemetery, but lately more are choosing cremation. When people are cremated, relatives often keep their ashes displayed in an urn, or spread the ashes someplace the deceased specified or enjoyed.
All of these things are elements of contemporary American culture. Just to give you examples of differences from other cultures: Inuits put old people on sea ice to die. Indians almost all have arranged marriages. Hispanics are seldom circumcised. Yazidis put their dead on the roof so vultures can eat them.