It's not that simple. Есть has two main meanings:
- A present form of 'to be' which is usually omitted in a modern language but is used in some expressions, notably: "У [somebody] есть [something]". Literally this means "There is [something] that is owned by [somebody]" but usually it is translated as "[somebody] has [something]"
У меня есть мечта - I have a dream = There is a dream owned by me.
- An infinitive of 'to eat'
Я люблю есть по ночам - I like eating at night.
- There is also the third meaning: Есть! is a standard answer to a military order, like: 'Yes sir!'
Ест is a single 3rd form of 'to eat'
Он/Она/Оно ест - He/She/It eats.
• хлеб (xleb) [xlʲep] m inan (genitive хле́ба, nominative plural хле́бы, genitive plural хле́бов) "bread; loaf": From Old East Slavic хлѣбъ (xlěbŭ), from Proto-Slavic *xlěbъ, from Proto-Germanic *hlaibaz, of unknown origin, source of English loaf.
• молоко́ (molokó) [məlɐˈko] n inan (genitive молока́, nominative plural *моло́ки, genitive plural *моло́к) "milk": From Proto-Slavic *melko, further etymology is disputed but ultimately from Proto-Indo-European *h₂melǵ-. Cognates include English milk, Albanian mjel (“to milk”), Latin mulgeō (“to milk”), Welsh blith ("milk"), Tocharian A malke, Lithuanian malkas, Latvian malks, and possibly Ancient Greek μέλκιον (mélkion). Doublet of мле́ко (mléko), a borrowing from Old Church Slavonic.
• яйцо́ (jajcó) [(j)ɪjˈt͡so] n inan (genitive яйца́, nominative plural я́йца, genitive plural яи́ц or я́иц*) "egg": From Proto-Slavic *ajьce, diminutive of *aje, from Proto-Indo-European *h₂ōwyóm, likely a vrddhi derivative of *h₂éwis (“bird”). Cognates include English egg, German Ei, Welsh wy, Latin ovum, Spanish huevo, Greek αβγό (avgó), Armenian ձու (ju), Persian خایه (xâye), Sanskrit अण्ड (aṇḍá).
It's not really supposed to be used in English, either, but I use it anyway. because it often makes much more sense to separate all the elements in a list. I never quite understood why you'd separate all the items with commas, except the last two. Sometimes, not using it can create ambiguity or even embarrassing statements, like: "The things I like about my family are my children, cat, wife and dog."
lack of an oxford comma cost a company 5 million https://www.cnn.com/2018/02/09/us/dairy-drivers-oxford-comma-case-settlement-trnd/index.html
I think the word "есть" in a declaratory sentence is used when the speaker wants to emphasize the declared fact either postively or negatively he/she was asked about. So, the correct answer should be "We DO have bread, milk and eggs." But, I shall welcome any counter-argument if I'm wrong, of course.
Nothing I've seen in the lessons supports your idea. I think you have to realize that у нас есть is a very idiomatic expression. It literally means "By/near us (there) exists/is....". That is quite far away from the English statement "we have", but the English is essentially what the Russian means, hence the highly idiomatic translation.
It may be that in informal or colloquial Russian, they drop the есть in positive declaratory statements, but I don't think that that is "good" grammar, at least from what I've learned so far.
And certainly, in negative statements, it can be dropped: У нас нет....
They are. Its is just that for neuter and inanimate masculine nouns its is no different that the base form. Here is the chart for банан, for example:
This masculine-zero-ending rule covers the usage of all plurals as well. The Accusative plural form is the same as the Genitive plural for all animate nouns (e.g., Я люблю кошек)—and the same as Nominative plural for all inanimate nouns (e.g., Я купил бананы).
ONLY the singular мама-type nouns have a unique Accusative form (e.g., мама→маму, кошка→кошку, Мария→Марию) that is unlike any other form.
I am by no means an expert in Russian, but according to what is taught in the Tips and note section, in this kind of constructions the things owned are actually the subject of the sentence and they are in the Nominative case, except when it is a negative sentence (not having something), in this case, the genitive is used.