There is no contradiction. There was a creation before Mahapralaya or prakritka pralaya. We are not in the time period of 7th Lord Brahma. We are in the manvantara of 7th Manu known as Vaivasvata Manu. I have given below the concepts of both pralaya and manvantara.
pralaya (‘dissolution [of the world]’)
The Hindu scriptures propound the cyclic theory of creation. The cycle
of sṛṣṭi (creation), sthiti (preservation) and laya (dissolution) goes
on endlessly.
The dissolution, called laya or pralaya, is of four types: nitya;
naimittika; prākṛtika and ātyantika.
Nityapralaya refers to the daily deaths of beings that are born.
Naimittika pralaya is the dissolution that takes place at the end of a
day of Brahmā, called ‘kalpa’ which is equivalent to 4.32 billion
human years. The prākṛtika pralaya is the dissolution of everything
into prakṛti (the basic matrix of the universe, often identified with
the māyā-power of God) at the end of Brahmā’s life of (his) hundred
years equivalent to 10^36 human years. Ātyantikapralaya actually refers
to mokṣa or liberation wherein a jīva is liberated from transmigratory
existence.
A Concise Encyclopedia of Hinduism by Swami Harshananda
manvantara
(‘period of rule or epoch of a Manu’) The concept of time as given in
the purāṇas is, to say the least, mind-boggling!
Each day of Brahmā, the creator, (called ‘kalpa’ by the purāṇas)
includes one thousand Mahāyugas. Each Mahāyuga includes the four
well-known yugas: Kṛtayuga, Tretāyuga, Dvāparayuga and Kaliyuga.
This day or kalpa is divided into fourteen manvantaras (epochs of
Manu) or periods of time, ruled by a Manu. Each manvantara has a
little more than 71 Mahāyugas.
The fourteen Manus ruling over these manvantaras of the present kalpa
are: Svāyambhuva, Svārociṣa, Uttama, Tāmasa, Raivata, Cākṣuṣa,
Vaivasvata, Sāvarṇi, Dakṣa-sāvarṇi, Brahma-sāvarṇi, Dharma-sāvarṇi,
Rudra-sāvarṇi, Ruci and Bhauma.
The Manu of the present age is Vaivasvata. He is the son of Sūrya and
is also known as Śrāddhadeva.
Each Manu has his own set of gods, Indra, ṛṣis and others. The name of
the present Indra is Purandara. The Saptarṣis or the Seven Sages of
this manvantara are: Vasiṣṭha, Kaśyapa, Atri, Jamadagni, Gautama,
Viśvāmitra and Bharadvāja.
In terms of human years, one Mahāyuga is of the duration of 43,20,000
years. Hence the period of a manvantara comes to 308 million human
years!
A Concise Encyclopedia of Hinduism by Swami Harshananda