Ching Ming - How do we honour our ancestors?

At Ching Ming Festival 清明節, 20+ people in our clan went together to Aberdeen pay our respects to my grandfather and his two wives, our grandmothers.  We have been doing that for decades and decades, twice a year.  I note that people honour our ancestors with a variety of offerings.  

Candles.  Incenses.  Flowers. 

Tea. Wine. Rice. 

Oranges.  Bananas.  Apples.  …

雞尾包。 

Roasted pork.  Roasted duck.  

Steamed Chicken.

Dim Sum.  Paper money.  

It is often said that the Chinese (at least some of them) believe that the dead continue to exist in another realm, where they have needs similar to the living, i.e., food, drink, shelter, clothing, money, …  Hence the custom of bring such items to the graveside on Ching Ming Festival, to show respect to the dead.  

Many Christians oppose such practices, considering them pagan practices, superstitious.  

In reality, only some people would leave such items behind, and usually only very small amounts.  The left-behind items will actually be cleared away by the caretakers at the cemetery, shortly after the people have left, for very practical reasons.  

Most people would eat what they bring at the graveside, or take them away to be shared later.  The sharing and the ritual strengthen the relationships that bind the clan.  

What if some people bring the favourite foods/drinks to the graveside do not really believe that the dead will actually benefit materially from them, but just to honour the memory of the dead?

How is it different from the way some Christians bring flowers to the graveside?  Presumably to show respect and honour to the dead?

Some claim that people started bringing flowers to the graveside thousands of years ago to mollify the ghosts of the dead who were believed to hang around the grave.  Some claimed that flowers were brought to funerals to camouflage the stench of the rotting corpse.  Christians simply picked up that practice.  The practice does not seem to be in the Biblical accounts.  

Some cultures do not being flowers, but something different.  Many Jews would place small stones on the grave.  For a variety of reasons: as a sign that the grave have been visited, that the grave is taken care of, to symbolise that the soul is permanent (like a stone), …

Bringing flowers to the grave is not necessarily Christian or Biblical.  And bringing the dead’s favourite food or drink is also not necessarily superstitious by itself.  It is not the act that matters. It is the motivation.