What is the first level of language structure?

There are a number of ways we describe languages. The first one classifies them according to their basic grammatical structures:

Isolating languages (aka analytic) -- ones that use invariable words, but have strict rules of word order to keep the grammatical meanings of things clear.
Included are Chinese, Indonesian, Pidgins and Creoles.
English is inflexional (see below), but has been moving towards being isolating.
Isolating languages are easy for adults to learn, but not as easy for children.

Agglutinating languages (aka synthetic)-- ones that add very regular prefixes and suffixes to main words in order to express nuances
Included are Finnish, Turkish, Japanese, Tamil, etc.
These languages are very explicit and logical, and easy for children to learn.

Inflexional languages (aka fusional) -- languages that use prefixes and suffixes, but also vary words to express nuances of meaning
Included are Indo-European and Afro-Asiatic languages.
Declensions -- variations on nouns (e.g. man, men, man’s, men’s).
Conjugations -- variations on verbs (e.g. sing, sang, sung).
Inflexional languages can be difficult to learn, because they usually involve many irregularities.

Amalgamating languages (aka polysynthetic) -- a much smaller group of languages that tend towards complex words that carry a sentence-worth of information.
Included are Basque, many Amerindian languages, and Klingon.
These languages are usually very difficult to learn, unless you are brought up with them. The Basques joke that they are immune to the Devil because he couldn't learn their language!

A second way of classifying languages is based on the word order they use:

SOV (subject-object-verb) is preferred by the greatest number of languages. Included are the Indoeuropean languages of India, such as Hindi and Bengali, the Dravidian languages of southern India, Armenian, Hungarian, Turkish and its relatives, Korean, Japanese, Burmese, Basque, and most Australian aboriginal languages.

Almost all SOV languages use postpositions ("therein lies a tale"), with a notable exception in Farsi (Persian). Most have the adjective preceding the noun. Exceptions include Burmese, Basque and the Australian aboriginal languages, which have the adjective follow the noun.

SVO (subject-verb-object) is the second largest group, but has the largest number of speakers. They are split between languages that use prepositions ("I go to school") and ones that use postpositions ("therein lies a tale").

Among the prepositional languages are the Romance languages, Albanian, Greek, the Bantu languages, languages of southeast Asia, including Khmer, Vietnamese, Thai, and Malay, and the Germanic languages. Most of these have the adjective following the noun ("un enfant terrible)", except for the Germanic languages, which put the adjective before the noun ("ein schreckliches Kind").

The second group use postpositions. These include Chinese, Finnish and Estonian, many non-Bantu languages of Africa such as Mandingo, and the South American indian language, Guarani. The first three have adjectives before the noun, the others have adjectives after the noun. Some linguists believe that Chinese is moving towards becoming an SOV language.

Next, we have the VSO (verb-subject-object) languages. In Irish, they say Cheannaich mi blobhsa -- “Bought I blouse” -- for I bought a blouse.

These always use prepositions. Although a relatively small group, it does include most Semitic languages, including Arabic and Hebrew, Celtic languages such as Gaelic and Welsh, the Polynesian languages, and a number of American indian languages such as Kwakiutl (British Columbia) and Nahuatl (Aztec). Most have the adjective after the noun. Kwakiutl and Nahuatl have the adjective before the noun.

Only a handful of languages put the subject after the object. Several northwest US and Canadian indian languages use VOS, including Coeur d’Alene, Siuslaw, and Coos. But the first uses prepositions and adjectives after noun, while the other two use postpositions and adjective before the noun!

There are also languages that use more than one of the standard systems. Notable of these is Tagalog and English. Strongly inflexional languages, such as Russian and Latin, often permit varied word order as well.